The TVTropes Trope Finder is where you can come to ask questions like "Do we have this one?" and "What's the trope about...?" Trying to rediscover a long lost show or other medium but need a little help? Head to Media Finder and try your luck there. Want to propose a new trope? You should be over at You Know, That Thing Where.
Harmless Enemy if the enemy is intended to be zero threat.
Poor, Predictable Rock if it's an enemy that only knows one tactic that has an easy counter.
If it's more of an item or manipulation to easily turn a normally dangerous enemy (especially if it's the only type around or is a boss) into zero threat, you may be looking for Easy Level Trick.
If it's something more like "wear a ring of fire resistance to make enemy fire mages less dangerous" (but there are other enemies around too), that's just smart play, isn't it?
Edited by KD
Mooks that literally can't kill you, may be due to Artificial Stupidity. Sometimes this occurs because the only form of attack they have is something you're completely immune to.
Edited by Devan2002