Slime Sword

It’s the unique equipment of Slime Village Area 1: any monster you defeat there can drop it. As a piece of the Slime Set it never drops at random.

Its effects count every hero’s level of it together: with all 6 heroes at level 10, 60 in all, ATK + 15 becomes ATK + 135. Disassembled, it gives Marble Bricks, like every Rare weapon. Once you’ve had one, you can craft more from the equipment dictionary when the Blacksmith reaches level 70: 40,000 Marble Bricks at first, more as your heroes level it.