Use Resonance against a Tyra. Her Fire Bomb will kill any clones you put on point anyway, so you might as well take Resonance so that every time the fire kills your clones, they explode and deal damage to the enemy frontlines.
Make sure either Grohk or his totem is dead before using your ultimate. Give about a second after the totem dies, so that the enemies' CC immunity wears off first. Otherwise, your Ultimate will do nothing when the enemies have CC immunity.
Agony is great against Terminus. He deals a lot of damage to your tanks, and it can be hard for some tanks to escape him. Stunning him gives your frontlines a chance to get away, and makes him vulnerable. Stunning him can also cancel his Siphon.