The 1st Edition cards shipped only in 11-card booster packs containing seven commons, three uncommons, and one rare, and about one in every three packs held a holographic rare
Create a 2/2 green Bird creature token with "Whenever a land you control enters, this token gets +1/+0 until end of turn." If the target is illegal when Choco-Comet tries to resolve, it won't resolve and none of its effects will happen
Most commonly, they grant +1/+1 to all your other merfolk, but many do even more, like giving abilities (such as islandwalk or ward), drawing you cards, or making your spells cheaper
The card is part of the Gym Heroes collection
Seismic Spike Seismic Spike is a Stone Rain variant that costs 1 more but it also gives 2 mana back
You can also explore all MTG sets listed in order to see how these expansion sets fit into Magics history