He has Aether Power (50% increase healing)
And his troop surely is with healing.
Edit: I’ve just found this guy, his Aramis has mana troop at 30 lvl (20% healing bonus) and as a ranger he could have (and surely has) 2% healing bonus (from 19th node).
But for an Atk hero,. reach such a high healing total, something is wrong with the hero’s planning. in the second atk when he hits 3 the cure reached more than 1250 for all heroes, not to mention that he has accumulated Extra life.
If this is not a BUG.
That hero becomes the best hero in the game, totally disproportionate to the others.