Sacrifice denies the enemy gold and experience while refilling your mana to keep harassing.

Frost Blast chunks the offlaner and slows them, so land it when they stand near creeps.

Frost Shield gives massive damage reduction, so pre cast it on your carry before engagements.

Chain Frost punishes grouped teams, so save it for when enemies cluster in fights.

Use the Frost Blast slow to set up kills for your cores and peel for yourself.

Position behind your frontline, you are immobile and die to any focus.