I have recently studied the matter on my Warleader. For more specific information check out the creep corruptions thread below this one. What I have found is you want 3 critical for the heals, Physical mits get you very little results for a Warleader. If I stack 3 of them I only get a 5% increase in Mitigations. Tactical is better with about 13% increase from 3. I would suggest stacking some mastery. If I slot 3 of them I get a 20% increase in damage and a 7% increase in healing. I usually stack some health for power and Crit def as well.
Landy Redrighthand WL 13, Pawpatrol Stalker 7, Horrorbuisness BA 7
Landy Tridis LM 6, Barnabras Warden 4