Nope, if you want your heals to crit you'll need to remove Will Destroyer since your crit is disabled.
Even if it doesn't give it +Stats, your crit is still disabled with it on. You will need to remove it and use Sniper's if you want to be a pure healer.
Most mages 60+ once in pve gear will drop Will destroyer for Sniper's + Determination. Since Mages in legend gear can gem in crit and get just slightly under archers in Crit. I've seen mages with over 10k Crit.