[Taqwus]

Tramplers have difficulty trampling anything that's ethereal, and can't trample anything that's the same size or larger. It's not too hard to get etherealness.

Try, say, a Bane Lord with a Robe of Shadows, a Snake Bladder Stick, and a Lucky Coin or Luck Pendant. It's fairly cheap, hard to trample, and will be spamming the area with poison gas *and* its innate chill aura. Or running against a C'tis front line of Dispossessed Spirits (ethereal, so hard to trample; *and* a cheap bulk summon, so easily replaceable) backed by Poison Slingers.

The AI doesn't really make plans of this sort; it doesn't even have a good grasp of what different magic items do, so it distributes pretty oddly