Since the Rng stuff has been such a big thing, maybe nintendo and sakurai will know about it easily enough and nerf a few things (like crits, whack/thwack, and maybe magic burst), but even with the rng stuff, i dont think hero is good enough to be really annoying. If anything it'll maybe just make the matches more entertaining.
As for the RNG stuff, I have a couple thoughts which aren't discussed a lot:
First, I think it'd be for the best if people started to group together spells. It makes it easier to guess what kind of spell's going to come up in general. Like putting Sizz, Sizzle, Bang and Kaboom into one category since they're straightforward projectiles. They have 20 (Sizz, Bang) and 16 (Sizzle, Kaboom) % chance of appearing respectively, and the combos Sizz / Sizzle and Bang / Kaboom can't happen on the same roll. Effectively, it means that those four spells are semi-reliable: Hero has a little more than a 1/3 chance to roll a straightforward projectile.
On a similar note: the offense buffs (Oomph, Psyche Up, Acceleratle) - all share the same relative odds of appearing (16 %) and can all appear on the same roll. In effect, their chance approaches 40-50 % on a roll.
Other groupings I'd suggest:
Disable / Stuns: Kacrackle Slash, Snooze, (Hatchet Man)
Insane Damage / Instakill: Magic Burst, Kamikaze, Thwack, Whack, Flame Slash (Hatchet Man)
Defense: Bounce, Zoom, Heal
Really niche / near useless spells: Hocus Pocus, Kaclang, Metal Slash
That's six categories in total. Not perfect categories either, but it's much easier to keep track of 6 categories of spells instead of 21 spells.
Also: Magic Burst does stupid damage even when Hero's Mana is near zero. We're talking 13-ish damage at 3 mana, 30 damage at 45-ish mana and 55-65 damage at 100 mana. If anything, that could use a damage / knockback scaling nerf and / or lag nerf.
Otherwise, I've been having not many issues with Hero really. My only other nerf would be slight nerf to mana gain. One could also argue that crit chance should scale with opponents damage like Whack / Thwack already do (with 1/8 chance at a certain %), but too many nerfs and it's going to be overkill.