I've got him, but don't have a good use for him. The primary problem is that his kit works against itself instead of synergizing:
- He's a self-healing, self-buffing, beefy (GET IT?) unit with Armored, so you should put him up front as a combination tank/attacker! ...except, no, that doesn't work, because then he'll take damage, and taking damage makes his ability do less and less.
- Well OK then, ignore his ability and just keep him up front to soak damage and match skulls! ...except, no, then he's blocking 3 colors, and will do so for a long, long time thanks to a huge mana cost, and that's a complete waste if you're specifically not caring about his ability.
- Fine, put him at the bottom of the stack and let him act as a sniper! ...sure, I guess, if you're willing to let his Armored trait go to waste, and let his Armor and Life buffs proxy for ability damage instead of making your team more survivable, and let yourself stare longingly at his 9,273,748 Attack that he'll never actually match skulls with.
For the closest possible comparison, look at War, another attack-y Mythic unit with a single-target spike ability:
- His Aspect of War trait passively boosts his attack, so you want him up front to match skulls. Plus every time you match skulls you give his Armor Piercing trait a chance to fire - synergy!
- His ability only ever gets stronger and stronger, so his position in the stack doesn't affect it. Plus in addition to its spike damage, his ability also sets him up to take advantage of his Pyromania trait - synergy!
- Since his ability sets him up for drastically increased skull damage, you want him up front to match skulls, and that's great because now we've looped back to point 1 again - synergy!
War certainly isn't broadly considered to be "one of the good Mythics", but at least his kit is coherent, purpose-built, and supports itself. By comparison, though Ketras feels extremely similar to War, his kit fights against itself and muddles his purpose and use.
And since the man said "complaining about a problem without proposing a solution is just whining", I'll throw out...hrmm...let's say...
- If he's meant to be a self-buffing tank and attacker (which is a great idea!)...
-- Don't have his ability scale on the Armor and Life that he'll be losing at the top of the stack. Just scale on the Attack that he's buffing himself with, maybe?
-- Give him something to ease the pain of his mana blocking. Not entirely sure on this one.
- If he's meant to be the coup de grâce for a looping team...
-- Have him support a looping team on his ability activation (conditional extra turn, or give mana to all other allies, or orb convert [though that doesn't really seem like his bag], &c).
-- Honestly, sitting back and sniping feels much too tactical for a "charge in and Axe All The Things"-themed unit.