Mage Slayer

Flying When this creature enters, you gain 3 life for each artifact you control.

Whenever another artifact you control enters, this creature gets +1/+1 until end of turn and can't be blocked this turn. Cycling W/U (W/U, Discard this card: Draw a card.)

As this creature enters, choose a nonland card name. Spells with the chosen name can't be cast.

Counter target spell unless its controller pays 4. You gain 4 life.

Defender Plainscycling 2, islandcycling 2 (2, Discard this card: Search your library for a Plains or Island card, reveal it, put it into your hand, then shuffle.)

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.) Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Flying At the beginning of your upkeep, you may put a feather counter on target creature. If you do, that creature has base power and toughness 3/1 and has flying for as long as it has a feather counter on it.

Exalted (Whenever a creature you control attacks alone, that creature gets +1/+1 until end of turn.)