Cheapest / Most efficient way for a human Wizard to not age?

Question

For plot reasons, there will be a time-skip measured in decades. The other characters are elves so they don't have an issue. I have a human wizard.

Since the DM is on board, we will simply hand wave it as some sort of weird magical side-effect if necessary, but we would prefer something close to a rules or setting based approach if possible.

So, what is the most efficient / cheapest way for my character to cease aging or at least dramatically slow aging?

The characters are currently 8th level but will likely hit 9th before the time skip.

Answer 1

Spend the timeskip in the Feywild

You say that your DM wants to give you some weird magical effect that prevents you from aging in your timeskip. The Feywild has exactly that. On page 50 of the DMG the Feywild's time warping magic is explained. If your character spends 1 day in that plane your GM can freely choose a time warping effect from the table there. One of which is that days become years. Meaning that if your wzards spends as many days there, as the timeskip is in years, they will only have aged a few weeks, when they exit the plane after the timeskip.

The only caveat would be that you need to find a way to the Feywild, but that is something your GM can either just handwave "you fell into a hole and it turned out to be portal" or make an adventure about it, which takes places before your timeskip. Perhaps a trip to the Feywild is the very reason there is a timeskip for you in the first place. Your adventuring party went in there, not knowing of its effects and emerges back in a world, decades in the future.

Answer 2

Out of action

There are various ways to be out of action for a period of several decades in a way that stops aging from being an issue. Petrification is a classic (from a monster such as medusa or from a spell such as flesh to stone), but there's also the imprisonment spell, or just getting dead and getting resurrection cast on you. There are probably a few other ways, but they all add up to the same thing: you're out of action for the duration. It's time travel the hard way, just missing out on decades until your release.

The other common element here is that you're largely dependent on an outside participant to fix the problem. De-petrifying is moderately cheap, and could just involve another party of adventurers finding you and deciding to free you, but imprisonment tends to requires some deep lore knowledge to figure out how to break it. Resurrection is expensive and generally requires the caster to know exactly who they're looking for, so this would require that somebody somewhere wants you back, you specifically, and badly enough to go to all that cost and trouble to do it, so it probably doesn't work on the 'cheap' level (though it might be free for you, other than whatever this third party wants to claim as payment of debt for the service).

A place with weird time

Some planes have wonky time that could make you avoid aging, though there's a downside. The Feywild is the obvious choice for this, but demiplanes or other places could have odd time-flow as well. You spend a few days or weeks there and come back to a world that's nearly a century older. While this does meet the need, it's not that different form the previous suggestions. Spending a few weeks in fairyland and winding up decades in the future isn't all that different from just getting petrified for the duration, but at least you don't need somebody else to pull you out of it, and it's free. You can just decide to leave at some point.

A place with no time

Now this is more like it. The Astral Plane is timeless. Creatures on the Astral Plane "don't age or suffer from hunger or thirst", so that makes a pretty good place to spend a few decades without actually getting old in the process. You do have to stay there for the duration (or mostly; you could occasionally pop back to the mortal realm for a few days provided you don't stay there long term), but at least the time is still passing for you in terms of experience. Getting to the Astral Plane in physical form might be a bit of a trick, but if we're handwaving an adventure, it's as good as anything else.

Cloning

It's a high-level spell, but the clone spell says

...you can also choose to have the clone be a younger version of the same creature. It remains inert and endures indefinitely, as long as its vessel remains undisturbed.

This is a shortcut to undoing any arbitrary amount of aging, if you can get access to the magic (possibly via a scroll or wish, or a favor to a more powerful spellcaster who's willing to give you essentially 3,000 gp and possibly rent you a closet for a few decades). You get old the usual way, but then one day you have access to a clone spell, wait until it's fully cooked, and then die -- and boom, you wake up in a pot, young again.

This is probably the best option if you want to be back to your previous age while still having actually lived the decades in between in a relatively normal way. Cost might be an issue, though you might explain that you made a fortune in your decades of life and then spent it all to get one clone spell that let you go back and start over. As stories go, it's not the strangest one.

Answer 3

Get petrified

A flesh to stone spell, or perhaps an unlucky medusa or basilisk attack, might leave you turned to stone, letting decades pass you by effectively unchanged until you're released.

When you are under the petrified condition,

A petrified creature is transformed, along with any nonmagical object it is wearing or carrying, into a solid inanimate substance (usually stone). Its weight increases by a factor of ten, and it ceases aging. [...]¹

You'll need someone to de-petrify you, but that can be worked out offscreen or be incorporated into the initial session of the post-timeskip campaign.

Depending on how you read the rules for petrification, the question of remaining aware of the world (and therefore sane) arises, though we have previously addressed the matter and the bulk of answers and upvotes agreed at the time that petrified people are not aware of time passing.

^{1: PHB 2014 p.291}

Answer 4

Use a Rod of Security (DMG pg. 197)

It's a very rare wondrous item, but if your character is aware of the problematic logistics of a decades long plan vs. their own time span, searching for this item could be an entire side-quest that prefaces the time-skip, or it could be a donation from a wizard family member of one of the elves, or... any number of things that don't necessarily mean you get to keep it when the time-skip is over. (Someone shows up and steals it before you can return it, starting the quest that ends your time skip!)

A rod of security can be used by a single individual for up to 200 days; while time passes normally for one inside, they don't age. After using it, it needs ten days to recharge.

This means for every 100 days of your life that you spend outside of the rod during the time skip, you get to spend an extra 2000 days inside the RoS, or just under 5.5 years. Doing some rough rounding, for every year you spend outside you can spend roughly 17 years inside.

Answer 5

You have a number of options - I would suggest Sequester

You ask for the cheapest / most efficient method, but that is going to depend to a large extent on setting-specific knowledge we don't have. Even as a wizard of 9th level, there isn't much you can do by yourself to achieve this, but in most campaigns you would have accumulated sufficient treasure by that point to purchase the scrolls or casting services of others that would allow you to do so - provided such items or services are available in your game world, which we don't know. Another big unknown is whether this is something that will happen to your character by accident (such as finding themselves in the Feywild, as Treespawned suggests), even if you, the player, are working with the DM to this end, or is something that your character is intentionally seeking out.

At your current level, petrification

While petrified, you cease aging. Although the flesh to stone spell is sixth level and just out of your current reach, as Treespawned mentions several monsters have petrification as a special ability. Basilisks, for example, are a mere CR3 and should be something your 9th level wizard could encounter or even seek out if they existed in your world. On the other end you will need a greater restoration spell to be recovered. While this is only 5th level (and 100gp in materials), it is not on the wizard spell list, so not something you could do yourself in terms of pre-scribing a scroll and gifting it to one of your elven party members. However, if any of them are a bard, cleric, druid, or artificer, as well as certain subclasses, they should be able to restore you at 9th level - or pay for someone who can, again assuming such services are available.

You mentioned that "Something that would be likely to drive a person insane...is less [desirable]". A petrified creature "is unaware of its surroundings", but it is not, RAW, unconscious or unaware of its internal state or thoughts. Thus depending on how your DM rules, petrification could either be a maddening mental prison or a dreamless, timeless sleep. The consensus at Does a petrified creature stay conscious (and sane)? is that prolonged petrification is not prejudicial to one's mental state. However, if a petrified creature is still a creature, and is not explicitly unconscious, your DM might not agree.

With access to 6th level spells, Magic Jar

If you can get a scroll of magic jar and have 500gp for a vessel, you can separate your soul from your body. During the time your soul is in the jar, your body is in a "catatonic state". It is not clear whether your body ages during this time. If not, you need only make sure your body is protected as well as the vessel is. If your body does age regardless, you can cheat by possessing a succession of young bodies and living out their natural lifespans, returning to the jar each time you need a new host body.

This is, in fact, what the Master of the Desert Nomads did in the classic X4 / X5 adventure modules.

Of course, possessing another creature for its entire lifespan might be considered an evil act in your campaign, since as MindwinRememberMonica points out you are permanently removing their agency. Perhaps you can use the bodies of criminals that have been condemned to death, since their lives (and agencies?) are already forfeit, or the bodies of orphaned infants who have not yet developed a sense of self.

With access to 7th level spells, Plane Shift or Sequester

Why travel to the Feywild, where time might be slowed, when you can go to the Astral Plane, where biological time does not pass? According to the DMG (47),

Creatures on the Astral Plane don't age or suffer from hunger or thirst. For this reason, humanoids that live on the Astral Plane (such as the githyanki) establish outposts on other planes, often the Material Plane, so their children can grow to maturity.

With a single plane shift spell to get there, and another to return, you can spend the entirety of the timeskip on the Astral, conscious and active, but not aging.

Alternatively, with Sequester

If the target is a creature, it falls into a state of suspended animation. Time ceases to flow for it, and it doesn't grow older.

Since time ceases to flow, we explicitly don't have to worry about insanity induced from consciousness of the experience. Further, the spell can end on a trigger - such as, "When my party members call for me", which means you don't need to worry about having access to a spell to recover yourself later. If you know the specific date you wish the timeskip to end, you don't even have to rely on others to perform some action. And you certainly don't have to take morally-dubious actions like possessing others. For the safest, most complication-free experience, I would consider sequester to be your best option available at the lowest level possible.

With access to 9th level spells, you have many options

Astral projection sends your spirit to the astral plane, but keeps your left-behind body from aging.

Clone will provide you with a younger version of yourself.

True polymorph can turn you into an ageless form (like a warforged) or a race with a much longer lifespan.

Any version of imprisonment would result in:

While imprisoned, the target doesn’t need to breathe, eat, or drink, and it doesn’t age.

One of the five options, Slumber, explicitly makes you unconscious, if you are concerned about insanity.

However, when any version of the imprisonment spell is cast, you specify the trigger that ends it, but:

the DM must agree that it has a high likelihood of happening within the next decade.

Arguably, anything that you intend to reliably not occur for decades wouldn't also have a high likelihood of also occurring within the next decade, and thus planning such a long imprisonment in advance might not be permissible.

Wish might not be powerful enough to grant immortality without some major consequences, but "I wish to henceforth age at the rate of an elf" seems reasonable to this DM.

Answer 6

Do a Dorian Gray-like effect. One thing would age in place of the wizard.

Say, we can have hair age for the wizard. If the wizard is in his 70s, the hair is pure white, but his face & everything else are all stuck in the age the spell was cast.

Answer 7

You asked for brevity, so here it goes. Within the available items and spells, a ring of wishes can solve the aging problem a few times, but becomes its own quest over time.

My best suggestion is a novel item like a ring, rod, or potion that creates longevity or some such. It's up to the DM, playing or not, to figure out the rules of the item. Again, a quest might predate your adventure to find this talisman in preparation for the main adventure.