this.color.setBlue(true);
// If an opponent controls a Forest and you control an Island, you may cast Submerge without paying its mana cost.
Condition condition = new CompoundCondition("If an opponent controls a Forest and you control an Island",
new OpponentControlsPermanentCondition(filterForest),
new PermanentsOnTheBattlefieldCondition(filterIsland));
this.addAbility(new AlternativeCostSourceAbility(null, condition));
// Put target creature on top of its owner's library.
this.getSpellAbility().addEffect(new PutOnLibraryTargetEffect(true));
this.getSpellAbility().addTarget(new TargetCreaturePermanent());