I wonder if the right direction might be to modify the runes so they add damage rather than healing. It’d help deal with the “buff Ragnarok” crowd in the middle tiers, where it sounds like gear imbalances can prevent him from being as damaging as intended. But it’d also give him less survivability, since he couldn’t heal as much, so he could be killed more effectively at the top tiers and/or by a strong defense.
It’d also mean that at the top he’d have more potential as a cleanup dragon and against undefended bases, but that especially against maxed bases he’d be more vulnerable to defenders, and to attrition. Just a little more glass cannon-y and a little less tanky.
As I think I’ve seen a few people suggest, it could come with a health cost, but then - as others have pointed out - that could be very hard to balance. After all, he’s a dragon that’s 50% high damage and 50% high healing. There’s always just the idea of knocking a couple percentage points off his healing spells, but that’d also be hard to balance I suspect. Some people would continue screaming that he’s too powerful (and honestly, some probably will unless he’s nerfed to uselessness) and some are already screaming that he’s been nerfed too much.
That burstable rage is really a necessity for him, though, or he’s a little too easy to render utterly harmless. I wonder if maybe it’d be more balanced if he just regained rage extremely rapidly over a few seconds. So instead of an instant +3 rage it’d be, I don’t know, +500% (or whatever) rage regen for a few seconds, and canceling out the whole rage-freezing effect of mage supershots. A little larger window for people to counter him, but still a reliable way for him to rapidly gain rage.