Teferi's Sentinel

Creatures you control get +1/+1 until end of turn.

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.) Target player takes an extra turn after this one. Return up to one target nonland permanent to its owner's hand. Exile Karn's Temporal Sundering.

1G: Add one mana of any color.

This land enters tapped. T: Add W or U.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.) Draw a card.

T, Sacrifice an artifact: This creature deals 2 damage to any target.

Pierce the Sky deals 7 damage to target creature with flying.

When this creature enters, target player mills four cards.