You can also download the SRD. It doesn't have quite all the rules, but if you're making up a bunch of them anyway.

They breathe fire from nuclear fusion. And can fly from all the helium that the nuclear processes generate.

What does that have to do with Karma?

Maybe it's an initiative roll.

The trick is to leave them permanently petrified instead of killing them.

Why would you kill the lich? Just cast Stone to Flesh and leave them petrified forever. If you really want to be thorough, you can trap them in a demiplane just before casting Private Sanctum for the 365th time permanently blocking it from interplanar travel.

I'd rather have the body with the soul kept in a constant state of euphoria.

And sometimes the official stats suck. The 2014 Tarrasque was just sad. And if Tabaxis get Cat's Claws, Cat's Talent, Feline Agility, and Darkvision, cats should have those too. Along with a jump height of more than -1 feet.

Fantasy hero: Slay the dragon

Donkey: Lay the dragon

Minecraft speedrunner: Yes

I've been reading it on Deviantart.

I was thinking of that as a house rule for Mutants and Masterminds (which has a similar system, but is much more generous with the reroll). I think it's better if you don't feel like you wasted the Hero Point because you rolled low.

That said, it works best if it's a success/fail type thing. I understand pathfinder has a lot of things with critical success and critical failure. I guess you get it back if you don't score better?

It depends. Did I learn Gentle Repose, and is that staff worth more than 2,500 gp?