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.

All that sounds great. I personally like a good tank Tarrasque. The encounter is more puzzle than combat. The players are hardly noticed until they deal something like 10% of its HP. With a solid regen, that's a significant scratch. Of course, this version would be boring in a vacuum, so there's a time pressure of it destroying a city. This naturally gives it three stages. Stage 1, players are basically safe. They can try strategies, do shenanigans, and the Tarrasque will be at worst impeded, but likely relatively unaffected. The goal is just to get its attention at all. Any turns it spends targeting the players are turns the city is safe. Maybe give the city a magical artillery piece that needs to be set up. Stage 2, they've delayed the city's destruction. Now the problem is the Tarrasque is looking their way. Their main goal shifts to some form of "survive". A clever party can lure the Tarrasque out of the city, perhaps into a trap if they had time. A lot of actions are spent maneuvering, escaping, setting up the trap if it exists. It's likely the Tarrasque fully heals during this stage, although that doesn't make it revert to stage 1. It may do so if it cannot get to them in any way, like a flyer 300' up. Stage 3 is whenever it catches them or springs a trap. This is a final fight. Unless they straight up run away, this is when the big damage comes out, when that artillery may show up, when the trap springs. If they cannot do consistent damage, they will run out of resources and lose. If they can, they'll win, job well done, they get the keys to the city, a celebration, all that.

I had a campaign idea based on Salt in the Wound. The players pass through Salt in the Wound, which is much smaller than it once was, then they go do some quest in a nearby cave system. Once they get in, the cave collapses behind them, and they have to fight their way through it. Once they get out, they find out what the earthquake was. Salt in the Wound used to be doing damage faster than the tarrasque could heal, and it soaked up a *lot* of nonlethal damage. But since it slowed down, it had gradually been healing, until today it finally escaped. The players just did their first adventure. They have no chance to stop it. At first, their quests are simply to help with the damage caused in the wake of the tarrasque or warning villages that it's moving towards. As they level up, they might get powerful enough to change its path, or fight off the various factions trying to use the tarrasque for its own ends. And once the players are powerful, they can finally defeat it. And they have a choice between bringing back Salt in the Wound, which is now more necessary than ever given all the infrastructure that was just destroyed, or killing it for good. Or maybe if they really want to, they'd have some shenanigans that let them control it.