Infected Liang or Cured Jade
I have this idea of a commander card that is mutually exclusive per account. Namely Jade (Dr. Liang managed to cure her) as GDI or Dr. Liang (Jade managed to infect him) as Nod.
Their ability gets upgraded but they change factions. So one has access to 5 cards and another 4 cards. This is actually a what-if scenario where one of them switches sides.
If Jade works for GDI, she gets the healer missile. It works like the catalyst missile but heals units in a 7 tile range (Friendly or not, for once you can heal your opponents base). The missile however still reacts with tiberium, causing all sorts of explosions. So if you target a chem buggy next to a talon, the explosion wipes both of them but spares and heals any unit that is not adjacent to the buggy but within range of the missile. Its cost is 120 tiberium.
If Dr. Liang works for Nod, he gets the explosive drone. It works like the original healer drone but the catch is, it explodes upon death. One has to micro it into the enemy at the end of its life otherwise it backfires against your units. It costs 60 tiberium to use.