[MtG] Darksteel Archangel, Lightning Echoes

[bury the year]

First card of any sort posted on this forum in... 4+ years? Woohoo? Mainly concerned about cost/PT balance on the former and relative strength on the latter. (And yes, I know the angel's last ability looks like metalcraft. It's not.)

Darksteel Archangel {10}
Artifact Creature - Angel (Mythic Rare)
Flying, indestructible
As long as you control three or more artifacts, you can't lose the game and your opponents can't win the game.
Mirrodin may yet be pure once more.
4 / 4

 

Lightning Echoes {R}

Instant (Common)

As an additional cost to cast Lightning Echoes, sacrifice an artifact.
Lightning Echoes deals 3 damage to target creature or player.

In the Oxidda Range, it's the thunder that comes first.