"It's a fine way to travel, if you don't mind the smell."

Slipstream Eel

This creature can't attack unless defending player controls an Island.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

The List

Commander Anthology Volume II

Slipstream Eel can't attack unless defending player controls an Island.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)

Commander 2011

Onslaught

Slipstream Eel can't attack unless defending player controls an island.
Cycling o1o
U (o1o
U, Discard this card from your hand: Draw a card.)

Cycling is an activated ability. Effects that interact with activated abilities (such as Stifle or Rings of Brighthearth) will interact with cycling. Effects that interact with spells (such as Remove Soul or Faerie Tauntings) will not.