Arctic Sliver

You must use at least one {s} to play Arctic
Sliver
Each sliver you control becomes a snow
permanent and gains: "{s}: this creature
gets +1/+1 until end of turn. Activate this
ability only once each turn. (Snow can be
paid with mana from a snow permanent.)
"Only a few members of the Riptide knew about the
separate Ice Vault Project. As such, the storage of a
dormant Species XR17 specimen was forgotten
when the Slivers overwhelmed the Wizards."