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'When this creature enters, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top. Whenever another Merfolk you control enters, put...
'{3}, {T}: Search your library for a Merfolk permanent card, put it onto the battlefield, then shuffle.
'If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.
'This creature can't be blocked.
'Flying When this creature enters, put a +1/+1 counter on target creature you control. {3}{G}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each...
'Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)
'When this creature enters, draw a card, then discard a card.
{1}{U}, Exile this card from your graveyard: Draw a card, then discard a card.
'Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)
'{U}: This creature gains islandwalk until end of turn. (It can't be blocked as long as defending player controls an Island.)
'Champion a Merfolk (When this enters, sacrifice it unless you exile another Merfolk you control. When this leaves the battlefield, that card returns to the battlefield.) Whenever this creature deals...
'{T}: Destroy target creature with islandwalk.
'Trample
Morph {G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)