With the addition of retro borders and limited number cards, some cards are both exceedingly rare and valuable
Primarily sticking to blue, black, and green cards, plus one red outlier, these can slot into a wide variety of situations and decks, generally with very little setup needed to play them other than getting past a few turns and casting a healthy number of spells
This was mostly recently seen in the Universes Beyond: Fallout Science
it's one of the better escalate cards in Commander, but in MH3 Limited I dont like the idea of main-decking a 2-mana spell that grants hexproof and indestructible for a turn
Celestial Armor Similar to Mithril Coat, Celestial Armor offers a nice response to targeted removal for one of your Creatures
Doesn't help that it has four defense counters either, which further worsens the card's overall practical value