Etherian Goblin Bomber

Bombers exist only inside the Old One's Army, and they skip waves. The opening tier holds them back at the start and the higher tiers front-load them, so a Tier 3 run has bombs coming at you from the first push instead of halfway through. Like the rest of the event roster, their gear and toughness track your own progression, so the same enemy scales up every time you clear a boss.

It throws bouncing bombs on the same awkward lob a Clown uses, so the dangerous ground is not where the thrower stands. The bombs skip past your sentries and land where you are holding position, which pushes you off your own firing spot. Kill bombers on sight and let the towers grind down the ground troops.

The nasty case is a Tier 1 attempt made straight after the world evil boss, when the Tavernkeep has only just moved in. You have neither the defense to eat a bomb nor the sentry damage to clear bombers quickly, and two at once will end the run on your Eternia Crystal. The banner needs ten times the usual kill count, so it is a long-term project.