I was working on stories about the crystal war timeline when I noticed how the soldiers we saw in the episode were all the same, so I tried to draw different kinds of soldiers to bring some diversity. 
So here are the basic soldiers and their description :
 
Crystal trooper : Mind controlled crystal ponies who constitue the biggest part of Sombra’s army. Since they don’t have special abillilties, they relly on their weapons and number to defeat their ennemies.
 
Crystal Mage : Crystal ponies who were given a crystal horn imbued with dark magic. Their magic is rather weak and is limited to shield and energy beams but it’s more than enough to kill someone. Their shield can block magic blasts and even lightning from pegasi but will break if hit by a physical attack ; a rock threw by an earth pony will easily take care of them.
 
Dead Wing Trooper : At the start of the war Sombra’s army, composed exclusively of crystal ponies, had very few pegasi in its ranks ; for this reason, cloudsdale remained safe for a long time, but as more and more pegasi from celestia’s army fell, their number increased and even the skies were not safe anymore. 
Resurrected by the power of dark magic, pegasi who served Celestia in life are now forced to fight for Sombra in death ; as their bodies is slowly rotting they are slower than a normal pegasus and wear no armor to increase their mobility.
 
Advanced soldiers: >>1285169 
Elite soldiers: >>1285186