These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Demonic Spider: The Atomic Tower. It has massive range, massive area damage, and can damage your monsters harder than anything in the game. Nothing can stop the damage once its launched. Not to mention how powerful it gets in latter waves... Thankfully, the missiles can be tricked by clever monster placement and can be stunned like any other tower in the game and has a low fire rate (0.10 shots per second meaning a shot every ten seconds).
Goddamn Bats: Arguably, the Bog Towers and Holy Towers due to their percent-based damage.