Finale of Devastation

Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Harmonize (You may cast this card from your graveyard for its harmonize cost. You may tap a creature you control to reduce that cost by an amount of generic mana equal to its power. Then exile this spell.)

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)

When this Siege enters, search your library and/or graveyard for a non-Human creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for or one mana of that creature's color.)

Search your library for a creature card with mana value X or less, put it onto the battlefield, then shuffle.

Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. That land becomes a 0/0 green and blue Fractal creature that's still a land. Put a +1/+1 counter on it for each land you had enter the battlefield under your control this turn.

Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control seven or more lands and/or Treefolk, create a 3/4 green Treefolk creature token with reach. (It can block creatures with flying.)