Here's a sweet little 1.5-Extended card, Liege of the Hollows. It's actually a deck idea, but the deck revolves around Liege.
For those wondering what the Liege does, he's a 3/4 creature for 2GG (from Weatherlight)
When he dies, all players may pay X mana, to put X 1/1 Squirrels into play.
Pretty crappy? Here's how to make him a gamebreaker.
Set up with cards that generate mana, like any Green deck would. Mana Birds, Elves, Rofellos, and Priest of Titania. Also, BE SURE TO PUT IN Seeker of Skybreak. If your Rofellos gets you 6 mana, 3 Seeker of Skybreak would get you 18 more.
Now throw in an Ashnod's Alter, allowing you to sacrifice creatures for 2 mana each, as well as Gaea's cradle, giving you G for every creature you have in play.
From here on, you basically won the game. Play a Liege of the Hollows, sacrifice it, and then get 30+ mana for 30+ Squirrels. Then, if you play another Liege of the Hollows, you can tap your Gaea's Cradle for 40 mana, Then sacrifice 30 Squirrels for 60 mana, giving you 100 Squirrels. Then play another Liege (draw it or recycle one), giving you 300 Squirrels.
In anycase, you only need 20 Squirrels to win the game.
Sacrificing them to Goblin Bombardment: 20 damage
Mob Justice: 20 damage
X Direct Damage cards: 40+ damage.
Overrun: 80 damage.
Play a group game, and then Hurricane for 600 and watch the look on everyone's faces.
Anyways, here's a 1.5 Red-Green deck that uses this to its advantage. In group games, this deck mops up too.
4 Llanowar Elves
4 Seeker of Skybreak
4 Priest of Titania
4 Liege of the Hollows
3 Sylvan Hierophant
3 Rofellos, Llanowar Emissary
Non-Creature Spells:
4 Ashnod's Altar
4 Rolling Thunder
2 Lightning Bolt
2 Goblin Bombardment
2 Mob Justice
2 Tooth and Claw
2 City of Solitude
4 Taiga
9 Forest
4 Mountain
3 Gaea's Cradle
4 Fireblast
4 Masticore
3 Shatter
2 City of Solitude
2 Lightning Bolt