When this card attacks a monster and inflicts battle damage to your opponent: You can increase this card's ATK and your LP by the difference, and if you do, this card can attack once more
When you dont have enough cards to fill a sheet, fillers can be added to the sheet
I can imagine it being a little too good for Standard

Advanced Search Sets Random Syntax Release date: 2020-06-17 Ugin, the Spirit Dragon Alpine Watchdog Angelic Ascension Anointed Chorister Aven Gagglemaster Baneslayer Angel Basri Ket Basri's Acolyte Basri's Lieutenant Basri's Solidarity Celestial Enforcer Concordia Pegasus Containment Priest Daybreak Charger Defiant Strike Dub Faith's Fetters Falconer Adept Feat of Resistance Gale Swooper Glorious Anthem Griffin Aerie Idol of Endurance Legion's Judgment Light of Promise Makeshift Battalion Mangara, the Diplomat Nine Lives Pack Leader Rambunctious Mutt Revitalize Runed Halo Sanctum of Tranquil Light Seasoned Hallowblade Secure the Scene Selfless Savior Siege Striker Speaker of the Heavens Staunch Shieldmate Swift Response Tempered Veteran Valorous Steed Vryn Wingmare Warded Battlements Barrin, Tolarian Archmage Cancel Capture Sphere Discontinuity Enthralling Hold Frantic Inventory Frost Breath Ghostly Pilferer Jeskai Elder Keen Glidemaster Library Larcenist Lofty Denial Miscast Mistral Singer Opt Pursued Whale Rain of Revelation Read the Tides Rewind Riddleform Roaming Ghostlight Rookie Mistake Rousing Read Sanctum of Calm Waters See the Truth Shacklegeist Shipwreck Dowser Spined Megalodon

It makes the deck a bit harder to shuffle
However, this must be talked about, even though I feel like Im beating a dead horse (pardon the expression, but at least I didnt make it Pokmon analogy)