Cloak - when the minion moves it becomes invisible to the enemy, if the enemy moves into or end the turn next to it, it decloaks and attacks the nerest minion. Minion cant be targeted by ANY spells, when it takes damage from any source it loses the effect.
Some sort of trap tiles that work on a similar way.
Decoy - basically creates 2 copy of the minion nearby, the decoy dose not do damage and will never counteratack. Dispelling the decoy just removes it. Would be interesting to see some support cards with it like you could change them into completely different minions.
Union - minions with union nearby gain buffs corresponding to what they give, think ZEAL.
Flank - when a minion attack from above or below gains the effect.
Formation - when when there are ANY minions next to the minion with the keyword in a specific way, the leader or group get the effect depending on the keyword.
Riposte - when the minion counterattacks the effect happens.
Mortar - minion can only attack OR move, never both, deals ranged damage in a 2x2 area.
Incorporeal - can move thru enemy minions.
Lancer - can attack 3 spaces in a + direction but only in those direction, can not counterattack if enemy is not in those zones. hits all enemies but damage gets halved for every enemy.
Morph - when the minion kills a enemy it changes form, stats and effects.
Equip - give a minion a NONDISPELABLE effect. losses the effect after it takes a certen damage or number of hits like ARTIFACTS.
Mindwarp - force actions of a enemy ON his turn. Like the minion moves towards you and attacks, triggers like a battle pet. you can also just move it away clearing a path for you.
Ugh made my head hurt from writing this. This i my first post btw so go as hard as you want. I got more things like this, even working on some weird generals on the moment, lore, looks and BBS. Tell me if you would like to hear it.