Thorns means you need fewer cards, hitting harder. I like to use Orc Sargeant with Vulture, for that reason. Opportunity means the vulture's hitting the card he's most likely to kill, which takes the card out of the match, and also restores one health, partly offsetting that thorns damage.
True, the problem is that Vulture is usually on Crowling's team! And Other cards available for Life with these abilities, like Parasityc and Cave Slug are slow and take a lot of mana. Besides all of them only get Scavenger at level 6.
Triage could also be interesting to regenerate wounds from thorns, but I can rarely fit the Herbalist into the team, besides that he also only has Triage at level 8.