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Currently though it takes me, a melee with 8 ps and a danish probably 10+ hits to kill a cata,
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It depends on what part of the horse you hit. With 2 well placed hits do the head of the horse you should be able to kill a cata. It is much easier to kill the rider. Why are some players trying desperately to kill the Heavy horse.You are even able to kill a well armored Rider(IF6) with an one handed weapon with only one hit.(Of course, cav at full speed).
Heavy cav have pros and cons:
+ hp & armor (allows you also to face 2h and polearm inf frontally, without fearing to get dehorsed by one hit)
+ bumpdamage- slow (easy target for ranged and light cav)
- maneuver (after the lance angle nerf this has become more important for lancers)
- high upkeepPS: I am also using a Cata, but I cant use it all the time.(upkeep) Most of the time I play Siege naked with a Staff, to gain some gold in order to play as Heavy cav.