You may exile two green cards from your hand rather than pay Allosaurus Rider's mana cost.
Allosaurus Rider's power and toughness are each equal to 1 plus the number of lands you control.

• Number: EG-2
• Rarity: R
• Power: 1+*
• Toughness: 1+*
• Type: Creature
• Subtype: Elf Warrior
• Mana cost: 5GG
• Color: Green
• Artist: Daren Bader