What is this battle you mention?

Also very boring mythic

I thought it was a cool one ;_; The battle is the climax of the story. I will talk more about it if i do any lore.

Being strong doesn't make a card a mythic, and it's a pump spell, not really exciting IMO, maybe add a twist?

so you just added a huge story element for this card? Maybe put it on some flavor texts? Or something?

Yeah; this is a combat finisher. Either "I got enough through, so splat" or "I smoosh your creatures, and splat you next turn"

It's a perfectly good card; but there doesn't seem to be anything on it that you can't do at uncommon.

The effect is too big for uncommon. But to be mythic it needs to be splashy, and this certainly ain't splashy. It's a solid rare (that should probably cost 1 more mana)

Buffings all your creatures for +3/+3 seems geared towards which this is lacking. It's weird to say the least that this would be mythic, but a card such as Titanic Ultimatum that was made in a block that specifically introduced the mythic rarity is merely a rare.