If we're looking for "Best white creature that costs 6" I'd probably throw Yosei, the Morning Star or Sun Titan or whatnot into the mix. This isn't really that, though. This spell scales... sometimes having an attacking creature be indestructible this turn will win you the game. You have to factor in the fact that this card isn't blank as long as you have two lands in play. The same can't be said about the rest of the 6 cost cards mentioned.

This card does seem too cheap to me... partially because this is the exact card that a Blue-White deck wants to play (with enough dual lands to not care about the heavy white restriction). If Rout was reprinted in Magic 2014 as a Mythic, I'd call it a great card, and I'd expect its value to hold strong. I can't see much value in making a board wiper that's this much better than it.

Sorcery speed could solve this puzzle. It's not exciting, but it works, and there are plenty of games where sorcery speed indestructibility would lock you into victory (especially if you made a red-white control deck). Kicked, at sorcery speed, this card can still be it's own better-than-Thundermare (I destroy the board except for Sun Titan. Now I swing with Sun Titan. Win.) A lot of people would react badly to sorcery speed indestructibility, though. It's a shame.

So it requires you to only use other white creatures. Six is still significantly less than eight.

Let's see what you could have instead for six mana. ­Felidar Sovereign 4/6, vigilant, lifelink: Win the game (but only if you have 40 life)

Maybe that's comparable with "Win the game (if your deck contains creatures)"? Mythic rares just stupidly break the power curve, don't they.

Looking at rare only, we find... Final Judgment a symmetric wrath (so yeah, you're allowed slightly better than that; though being allowed to have "All my creatures are indestructible" at a lower cost is pretty damn nice)

Heck; even Jareth, Leonine Titan the white titan isn't very good!

i know people want to make the coster bigger, bust just look how much white mana you need to spend with it, this card is really hard to play with anything but monowhite you need 4 Whitemana to get it of. so no W/? control decks or anything similar i guess this is only usuable in a Monowhite deck tbh.

It's "cast this, win (with practically any other cards in play)". So 8+.

Regardless of the wording, what's a fair cost for a one-sided white wrath? It seems like in many cases a one-sided wrath will be better than a 7-cost martial coup. Plague Wind cost 9 in black.

I'm pretty sure they'd never want to print that line on a new card. It's horribly confusing text and is the kind of thing that would only appear in errata.

I like this card. It kinda reminds me of Martial Coup: people will put it in their decks as a Wrath, but it only manages to be a Wrath once you hit its special criterion. By contrast, Kirtar's Wrath is always a Wrath, and it's the bonus bit that might or might not happen.

When it's unkicked, this is a common effect: Rootborn Defenses. It's a little odd to see a mythic whose unkicked effect is common. Not that different from things like Mizzium Mortars or Kavu Titan, though, I suppose.

You could have used the rider from Gilded Drake ("This spell can't be countered except by spells or abilities").

lol forgot to change the text, it supposed to be kicked to a wrath.

The kicker is supposed to be a Wrath, I thought.

Um...what? Making creatures indestructible for 2 mana now seems fine, but quadrupling the cost in order to gain (the weaknesses of) a target and add a redundant effect since you're presumably already making it indestructible anyway?