Perhaps there can be an additional spectrum of equipable items, that would go in the weapons slot. Some of the gremlins that fled to Emberlight must have been healers, right? Maybe the Knights can convince them to teach them the craft, and open up a crafting path for the Wrench Wand, as well as making new craftable items? I've been playing for just a couple months now, but seeing the way the game flows, a healer would be nice to add to the party. Guns, swords, and bombs allow for a variety for players, but health management was one of the problems we've always had. Some runs, there would be only one or two capsule drops. I know that this is part of the challenge, but many runs have been spoiled by premature deaths. Anyway, it was just an idea I've been sitting on and thought I'd share. I'm sure I'm not the first though.
Healing class/items
I wasn't around for the Grinchlin Assault, but I can understand where you're coming from. There would obviously have to be a cooldown, or a long charge. The 5* charge could be used as an AOE where you heal an area much like t3 healers do. And the way I see it, that wouldn't necessarily be abuse, but rather the intended use. Perhaps if there is a healer in party, less hearts drop, or there are fewer or no health pads on levels that have them.
Or you could make it so the healer uses his own health which would then heal an ally, and maybe have it so the 5star wand allows you to revive teammates with health?
I think we have all the healing we need. besides, no long charge or cooldown can stop me from waiting. we have life leech in seraph's HA (sorta), and that keeps the party alive in pretty much all situations.
I've never partied with anyone who had Seraph later on, so I wouldn't know the full effects of HA. Everyone so far has had Drakon, and that's what I've based my suggestion off of. Drakon seems to be much more popular, but that just might be chance that that's most of what I see..
Unless you can find a way to limit the amount of health healed (for example, someone suggested a life leech, and Seraphynx is the Sprite that increases the chances of an enemy dropping hearts), then this can be easily abused by healing everyone to full health prior to a major battle; take Grinchlin Assault for an example.