King of the Swamp King of the Swamp has mediocre stats of only 500 ATK and 1,100 DEF, but its effect to be substituted for any one Fusion Material or be used as Polymerization is powerful
Not only are they one of the coolest decks out there (being based off of the Star Wars movies), but they have some of the most powerful effects out there too
The most likely reasons are if it's sacrificed, if it's legendary and another legendary permanent with the same name is controlled by the same player, if it's a planeswalker and another planeswalker with the same subtype is controlled by the same player, if it's a creature with toughness 0 or less, or if it's an Aura that's either unattached or attached to something illegal
ST24-09 U Digimon Lv.4 Sunflowmon Color Green Cost 4 DP 5000 Digivolve Cost 1 Green 2 from Lv.3 Form Champion Attribute Data Type Vegetation/DATA SQUAD Card Text 1 [Special Digivolution Condition] [Digivolve] Lv.3 w/[DATA SQUAD] trait: Cost 2 [Effect] [On Play] [When Digivolving] You may suspend 1 of your opponent's Digimon or Tamers
Also, like Legatia, it responds to not only Synchro Summons but also general special summons, so you can use the search effect without any problems even when using revival cards or Parangx