Very often later in a format, once people have figured out how to combat the dynamics of aggressive decks, the card advantage of blue tends to dominate
EX6-041 U Digimon Lv [Main] By paying 2 cost and placing this card as 1 of your [Legend-Arms] trait or 1 of your level 5 Digimon's bottom digivolution card, until the end of your opponent's turn, 1 of their Digimon gains "[Start of Your Main Phase] This Digimon attacks." [Your Turn] [Once Per Turn] When an effect adds to this Digimon's digivolution cards, it gains Blocker and Reboot until the end of your opponent's turn
New Ability Word: Celebration The Phyrexians have been defeated, and that's cause for merriment
Gaining the extra 120 HP means that Darkrai EX will almost always have to hit Kyurem three times before Knocking it Out
The only known cards for this type of rarity are apparently misprinted versions of the two original Secret Rares: "Gaia the Dragon Champion" and "Tri-Horned Dragon" from the original Legend of Blue Eyes White Dragon booster pack, with the "Tri-Horned Dragon" being the much rarer card
Note, Im not going to include effects like Makeshift Munitions which always deal the same amount of damage no matter the sacrificed creatures power/toughness