[Joseph Jostar]

In the Colossal Tower, or at the very least its first encounter (the firespitters/lava slimes, I haven't been able to test the rest), you seem to gain the full amount of EXP, murai, and item drops from each enemy killed. With a Red Letter equipped in particular, it makes grinding items/money/levels a trivial affair. Especially with AoE spells like evoking Whirlpool.

Considering the treatment the arena got shortly after its introduction, it seems like it's worth asking if it's intentional or not.

Additionally, the firespitters in the tower fight are lacking the trait that makes their fire damage bypass immunity/absorb. So that's why the Red Letter thing is a thing.