Troll Block

The Troll Block room is a secret room that contains a single key wall (or sometimes 2 or 3) and one or two keys.

The room design is intended to indicate that you are supposed to use the key in the block. However this will mostly just waste the key.

How it works
Troll blocks have a $$100*\frac{key\_pillar\_count}{20}%$$ chance of dropping loot.

key_pillar_count represents how many troll blocks you have opened on your save file. E.g. if you have opened 10 blocks, you have a 50/50 chance of getting an item. The key_pillar_count is reset to 0 if you are successful with getting an item so with that reset.

This means that every drop requires on average five keys with a maximum of 20 if you are absurdly unlucky (1 in 43 million).

key_pillar_count can be found as one of the upgradeStrings inside the Save.json file. It does not increment when you open normal locked blocks.

EightyTwo said in the Discord that it is a ramping 10% chance. However, after digging into the code to gather the loot percentages, the code indicates it is a ramping 5% chance.