The idea is rather simple really, we have Mounted Slayers and Mounted Impalers which are completely different than their infantry counter parts. So, why not go a step farther? While MS and MI are both very good at general combat and are good at their roles, what orcs seem to be lacking to me, is a *light/speed* centric Calvary. For example:
Infantry version: Goblin Raider
Speed: Lightning Fast
Squad Size: 15-20
Abilities: Charge *melee Calvary no brainier*, a version of goblin tribal healing *slightly stronger, not much perhaps?*, Howl from regular wargs *shouldn't be OP on a unit this much weaker than the standard Calvary*
Formations: Battle, Interception *lots of increased speed more than other stances, but take slightly more dmg from hits taken*
Infantry version: Goblin Prowler
Durability: very low
Squad Size: 15-20
Abilities: Evasion *i know its a raider ability, but charge doesn't fit*, a version of goblin tribal healing, fire arrows, and howl.
Formations: Battle, Serpant
What would need to be done is that ensure that neither of these are able to completely replace MS or MI. the Ambusher is fine in that standard since it would have a completely different style. MI and Strikers though are quite similar, however, i imagine the striker would be a lot more of an active one. MI you can rush in and kill and rush out usually. If Striker was made to capitalize on speed and nibble them down slowly, hit withdraw, hit, withdraw taking multiple attacks to kill perhaps, but due to speed being able to do so without fear. That would make MI the in between of the Striker and the MS, which would allow people to choose if they want to specialize it or not, or if they want flexibility or not. The numbers that they have more than standard calvary is to stick with the goblin theme of always having more than their enemies, which, also tends to decrease individual unit str.
"To underestimate a Goblin Horde is to stare into the face of Hell and think it to be heaven." ~ Svulnar, The Goblin King