Runestone Keeper

In one of your runs you might find a strange item, a coin.
Using the coin has a 50% chance that will instantly kill you and give you this achievement.
The other 50% chance will completely heal you.

The first time I tried this runeword I got killed in a few turns on floor 1.
As It turns out, the explosion damage (33% chance) is based on YOUR current ATK damage not the Enemy's.
So, to win this, run around without any weapons so the explosion do minimal damage, once you discover an enemy, switch to your main weapons and go to town.

Oh yeah, if a mist tile gets uncovered by other monsters, bomb traps or your equipment, it wont count as revealed by you and the lucky effect wont trigger, so only tiles you actually click on and uncover get affected.

The only way to get to level 12 is by having the 3rd tatoo from the God of Treasure which let's you level two times more past level 10.

This boss only spawns on Chaos mode.
But you have 1 in a 3 chance of seeing him on floor 25, however, if you get another boss, you can quit to main menu and the game will reroll the boss in which case you can keep doing that until you get him, he looks like an Octopus.

The boss has a ranged attack but not the minions, the minions will drop hearts for you to heal but depending on how much you can heal from them, it might be better to ignore them and keep attacking the boss instead.

I got lucky and grabbed God of Evil after having God of Contract early, contract God gave me a lot of stamina to increase my HP and Evil gave me durability for the fight.

You can also use Runewords for your Chaos run, Lucky will help you along the path to floor 25 but not much on the Boss fight, "Fresh Blood" however will give you lots of ATK but you'll have less HP but you can get over the low HP by picking Azir and reloading a floor around level 15 and getting hearts from enemies to increase your HP, looking into Arenas until you find the God of Contract will also help a lot to get your HP up not to mention those altars that take Runestones to give you +10,+20 or +30 Max HP.

Around floor 18, look for the item that removes all your debuffs and keep it until you get to level 24 and use it then, you dont want any debuffs going into the boss fight.