Never used Come at me, but pretty sure it’s a passive feat, not an active one. I also just googled the Warden feats because I can’t be bothered turning my Xbox on to look, but the description the website gave is:
Come at Me – Passive feats – You’ll gain more Renown from kills, however you’ll receive more damage.
It says nothing about healing, and you can’t activate it which means it’s always on. So basically with that feat you’re going to earn feats quicker, but you’ll also die quicker. Considering how quickly you can earn feats at times as well, this feat is more damaging to you than helpful. Only healing feats Warden has is Body Count (killing minions), Second wind (activate for a health buff) and stalwart banner (continuously heals you and allies within a radius.