Natural Order

As an additional cost to cast this spell, sacrifice a green creature.
Search your library for a green creature card, put it onto the battlefield, then shuffle.

Mishra's Bauble

{T}, Sacrifice Mishra's Bauble: Look at the top card of target player's library. Draw a card at the beginning of the next turn's upkeep.

Show and Tell

Each player may put an artifact, creature, enchantment, or land card from their hand onto the battlefield.

Ornithopter

Lotus Petal

{T}, Sacrifice Lotus Petal: Add one mana of any color.

Worldspine Wurm

Trample
When Worldspine Wurm dies, create three 5/5 green Wurm creature tokens with trample.
When Worldspine Wurm is put into a graveyard from anywhere, shuffle it into its owner's library.

Mox Opal

Metalcraft — {T}: Add one mana of any color. Activate only if you control three or more artifacts.