People who play card games know that card advantage is king, and if your opponent doesn't have any cards then they can't play the game, so discard is a particularly scary mechanic for card gamers
Sanctioned play: its a hard no (and sleeves dont fix it) If the event is sanctioned , you should assume gold-bordered cards are not allowed , full stop
Mythic Wildcards are, as you would expect, the hardest to obtain
Abilities: At end step, if you've played a land or spell outside your hand this turn, deal damage equal to its power to any target
Lose Focus is interesting in that it scales with the game, and even later on, it can snipe spells when an opponent is tapped out for very little investment