Frog Traveler

Other Frog creature spells cost {1} less to cast.
Whenever a red-green Goblin creature leaves the battlefield, you may pay {1}. If you do, add one mana of any color to your mana pool.
{t}, {2}: Put X 1/1 red-green Goblin creature tokens on the battlefield where X is the number
of creatures that left the battlefield this turn.
Ribbit!