Cavalry Mode Tacticsguide

[Corndog]

[quote author=Trialsking link=topic=38716.msg217139#msg217139 date=1421817904]
For pikemen some polearms can't be used on horse back. The long stabbing ones like sarissa can't be used in horseback but slashing ones can.

Any polearm longer than a certain length is unusable on horseback at all.  Of the Legendary Polearms, the only one that can is Navel Glaive, I'm 99% sure.  I do not however remember what that length actually is though.
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Thunder Pike is usable too