vs 
Zed objective - Use Death Mark to kill a target that Shen is channeling Stand United on, and kill the target. - Reward: Death Mark dispels any instance of Stand United on the target if active and prevents Shen from teleporting, instead of dealing damage.
Shen objective - Use Stand United to save a target that Zed has used Death Mark on, and kill Zed. - Reward: Stand United dispels Death Mark on the target if active and prevents Death Mark from generating a shadow for Zed, instead of shielding damage.
vs 
Azir objective - Slay Xerath with at least 8 soldiers active (Includes the soldiers summoned by Emperor's Divide). - Gain 1 additional charge on Arise!.
Xerath objective - Slay Azir after hitting him with at least 3 uses of Rite of the Arcane. - Gain 2 additional uses of Rite of the Arcane when cast.
Probably overpowered rewards, but I don't care. This is just for fun.