2000-5000 (depends on selected difficulty)
2 (+1 per upgrade)
25 (+1 per upgrade)
The stank appears in the map Left 2 Die as a zerg NPC unit. It has a boss bar when appears. Every once in a while it will do an extra powerful attack that makes a small hole in the ground and damages everything around it. The hit points increase according to the selected difficulty (ranging from 2000 on casual to 5000 on brutal).
On "Night 2 Die" mode, the stank gains hit points with each appearance.
It has its own portrait in the map editor but uses the ultralisk portrait in-game.
On hard difficulty, killing a stank with no losses for it yields an achievement.
Kill a Stank before it kills anything on Hard difficulty.
Both players receive it, no matter who killed it.