Healing Charm can triple-dip from Divine Favor (priestess ability), Ring of Asyra and Enchanters Ring. This in and of itself makes it far superior to Bull EndurAnce.
The triple dip is appealing, but if you were going to cast two rings, would they really be Ring of Asyra and Enchanter's Ring and not a Dawnbreaker Ring?
I'm always happy to be proven wrong about cards I doubt: I like a diverse meta. I guess we'll see when it's available to everyone.
The other notable thing is that while Healing Charm can be seeking dispelled, it is "resistant" to purge/destroy. When a purge or destroy is declared, you can reveal healing charm and resolve the healing prior to the Resolve Spell step.
That's a good point, and one I totally missed.
The main reason you'd keep healing charm unrevealed is if your creature hasn't taken 8 damage yet. (Since there is a 0.4% chance you could roll 8 healing)
You'd wait till 8, really? This seems like a "push your luck" situation. A bad surprise or an unlucky roll could kill your creature while you were looking for a .4% improvement to your expected value. It's obviously context dependent, but generally if I healed 7 on a creature with only 6 wounds, I'd just be happy to have rolled the 6 and write off the wasted point.
The other reason is to trick your opponent into not killing your unit, for example if it has 1 health left and is stuck in a poison gas cloud. Your opponent might not bother finishing it off if he thinks it will die anyways, so you save healing charm until just before the next Upkeep phase.
Yeah, that's what I meant by misallocation of resources. And it's an okay tactic, but in this case the creature's still going to be awfully near death. In your example, my creature heals ~4 and then takes 2 damage is is left at ~3 health. (There's a chance I only heal 1, but let's not worry about that too much.) Then, if I have initiative, I get to try to rescue it with teleport/force push/whatever in my quick cast phase, or I can use it for one more attack before you kill it. If I don't have initiative, you get a second chance to kill it in the quick cast phase, but you're probably not prepared for that unless you have Arcane Zap or an elemental wand/thoughtspore. Then you get to activate a creature before I do and probably just finish the injured critter anyway.
I mean, sometimes it'll work beautifully, but it doesn't seem like the reason to include the card. Minor Heal seems better, and that's only borderline playable?