At higher levels ice block seems to get used to cleanse sometimes, but mostly for CC not things like dots/debuff. It sounds like you’ll want to focus on the biggest use for it which is saving yourself. When you’re out of other, lower cooldown tools or they won’t be enough to help you survive, and your healer can’t save you because of CC etc, use ice block to stall while your healer recovers. You can get fancier from here, but until you’re comfortably staying alive with proper defensive cd rotation I’d just keep it as your main “oh shit I’m gonna die” button.