Does the use of wish to recover from this count as one of the safe usages, or does it have the chance to fry itself out of your brain?

Id count it as safe as a dm

RAW, it's not replicating a spell, so the effect weakens you, 1/3rd chance it burns out, all that, except the DM doesn't rule on possibility, since it is called out as possible. I treat every effect that specifically call out Wish as removing it as using Wish to replicate a spell. Unless the intent was to only allow a Wishing magic item to work, it'd be pretty ridiculous otherwise.

I'd say it gets you the exhaustion, but as long as you not actively mess up the wording the spell will work, since it’s specifically said that the spell can be used to do that so it should be able to do so consistently.

My wish would be the extinction of the sphinx race. Dirty tricksters.

*Get's transported to a time where all Sphinxes have died.*

Wow, they really don't let you have fun in 5e do they?

Not with Wish, that's for sure. Ive heard it said that anything past level 15 or so, they just didn't intend for real gameplay, and I have to agree. The Tarrasque is defeated with a Fly spell and a bow, Wish can technically be used for other things but really is just Lesser Wish from older editions, only spell replication, and capstones tend to be meh and really feel tacked on most of the time.

I think the only capstones really worth it are from Cleric, Paladin and maybe Barbarian or Artificer. Fighter is cool, but also a bit lackluster.

You'd need a magic bow. Or better yet, a bow with the Repeating infusion. Also, they improved it in the 2024 version. It has a 150-foot ranged attack and a Burrow speed for if things go sideways. I think they could have done better, but at least you don't have to worry about Aarakocra poachers driving them to extinction.

The problem is if it gives you the exhaustion, there's a 33% chance you can never cast Wish again, so you can't do it consistently.

I'd expect that going over 7 creatures limit is unsafe (but I've never actually played dnd)

I meant consistently as in "has no chance of failure". Wish is already powerful enough and is likely intended as the "brute force solution" anyway.

True I forgot that detail. Sacred flame would do fine, as well. Those level 1 aarakocran clerics might die by being tapped and falling the whole distance but they'll bag a tarrasque no problem. As for the 2024 Tarrasque, they *downgraded* it to resistance against physical damage, instead of immunity to nonmagic physical. I mean, it's nice that it resists magical physical, now, but any source of advantage to cancel the disadvantage of being in long range lets you kill with any bow/crossbow. Repeating would still be ideal, for ammo usage, but it needed its regeneration back. At least if you needed 100 aarakocran to start reducing its HP meaningfully, it'd be beyond the scope of "first time player who thought flying sounded cool".

Sacred Flame as a range of 60 feet. There's no rule that Tarrasques can't throw stuff, and they look like they have hands, so reasonably even in 2014 they could. They'd have disadvantage throwing something at a target 60 feet away, but they'd need a lot fewer hits to land. > Repeating would still be ideal, for ammo usage, but it needed its regeneration back. I agree. You can't outright *kill* a tarrasque so easily anymore, but being able to put them on the run so easy isn't great either. They also should have better ranged options. There are plenty of ways to outrange them. And a burrowing speed is too good. It doesn't just stop cheesing. It stops players from fighting them legitimately. Personally, I'd bring back regeneration along with the attack they used to have where they shot spines, or maybe give them a godzilla-inspired breath weapon, make it so anyone they hit is knocked prone. Once you get them to half health or down too many Legendary Resistances (though I'd probably change the Legendary Resistance mechanic so it costs HP instead of having three of them), they start digging, bringing you to the second stage of the boss fight. I'd make it so at high levels there are options to follow them undergound, but give the Tarrasque additional Lair Actions with "underground" being its lair. Maybe even have a final stage of the boss fight where it emerges in the Underdark and you also have a bunch of creatures from there to deal with.