Your best card singlehandedly is Thunderlord 4, 5 works as well. Thunderlord used to be a niche card for Spirit's Domain, however since all of Grohk's staple cards being nerfed, those being Crackle, Healing Rain, Outreach, and Gale. My Spirit's Domain looks like this, followed by which items I rush for.

Items you buy depend on the matchup, more than 70% of the time it's going to be morale boost, however if you have 2 tanks, which is unlikely in this situation, you want Chronos to keep slamming down totems. Your next item would either be Chronos or Deft Hands, personally I prefer rushing Deft Hands first because you need tier 2 Deft Hands for maximum value. Then you rush Chronos or a defensive item if you need it.