How do you defeat Arnold on zombie farm?

Answer 1

His pirates are tough but they attack very very slowly so he's beatable at lvl 20

Keep your Zombies hungry is very important for this level, use instant-hunger

My Approach is 1~2 flamehead, then 1 flower, followed by a few imps/amazombies/zombots, 2 more flowers and follow up with zombrutes

The key point is to keep your first flamehead alive till the end

However with current mutations available the first 2 flameheads will inevitably get one-hit killed, so I usually stock up few flameheads so the raid could go on.

All my zombies are mutated of course.