Annoying human players falls under two kinds: hit and run or getting the attack unit killed(like sappers). My favorite hit and run is with mages, have a invisable mage blizzard defenses, expensive things, and pleasants. Sometimes you need to sacrfice a mage to get the pleasants. You can also sacrfice a death knight by casting unholy armour on it and make it march into a city, then do a death and decay on itself. Death knights are at a disadvantage up against human nations, because of exorcism, and polymorph.
A sapper can't get past two guard towers without getting killed, so they are just best for enemy defense bombings.
Catapults are only good in groups of 3, where they can take down a tower easily with one shot from each cat'. Then, you may rush in.
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