Ivern vs Master Yi

Place your groves, then go gank while they grow: Friend of the Forest (passive) lets you free the camp without fighting it once the grove is fully grown.

After landing Rootcaller (Q), ping your team: allies who attack the rooted target dash into attack range, and you can dash to the target by recasting.

Cast Triggerseed (E) on the ally who engages: the shield explodes after a moment and slows enemies around them.

Recast Daisy! (R) to give her a target: her 3rd consecutive auto on the same champion knocks every enemy hit into the air.

Against Highlander (R), don't run alone: regroup with your team, because he gains speed and ignores slows.

If you have CC other than a slow, land it right after Alpha Strike (Q): during the strike, he's untargetable, and Highlander (R) ignores slows.

If you have CC, interrupt Meditate (W): he channels it to heal, more at low health, and to reduce the damage he takes.

Put pressure on his jungle early on: Master Yi is strongest once he has his items, and each stolen camp delays him.