Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Blue creatures don't untap during their controllers' untap steps.

At the beginning of each player's upkeep, that player may choose any number of tapped blue creatures they control and pay for each creature chosen this way. If the player does, untap those creatures.

Haste

Red legendary creatures you control have "bands with other legendary creatures." (Any legendary creatures can attack in a band as long as at least one has "bands with other legendary creatures." Bands are blocked as a group. If at least two legendary creatures you control, one of which has "bands with other legendary creatures," are blocking or being blocked by the same creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)

Mountain Valley enters tapped.

, Sacrifice Mountain Valley: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

, Discard a card: Draw a card.