This is basically Addons but XA Corperations exclusive, idk why i made the text huge ;D.
Revenge: When the unit equipped with it is destroyed, the unit that destroyed it takes damage, if it is equipped to a large unit then it does a lot of damage, if it's equipped to a troop then the effects are lowered. Cost: Low (troops). Medium (anything larger) High (anything very large).
Tamer: The tamer is used to make individual wild animals friendly e.g the Predator. Price: High.