I being a life wizard my self also ponder over this. What I am doing and seems to work is have either high damage for 1v1 or have high resist and healing (out and incoming) for 3v3 and 4v4... At the moment I do more 1v1 with a damage of 85. My critical block is lower and same for most of my resistance, but I can pack a hit with a rank 6 card.
Another idea is to get better gear. Try crafting gear, I just started this my self because I thought there was no need for craft gear, but I was WRONG. Hopefully something that I have said has helped.
Ps. One last this is to get a pet that has all the needs. -Resist (proof and defy) -Heals (sprite, fairy and unicorn)
Or one with mostly damage and heals. (what I use) -Damage (pain giver, lifegiver, life dealer) -Resist (proof) -Heal (fairy)