This has the potential to go on and on as players sacrifice more and more lands to try to out-tempo one another
Krark, the Thumbless At least upon losing the flip your spell goes back to your hand, and it still counts as being cast
Even the Magic: The Gathering cards you dont think of can be worth a fair amount
Like its other recent banned compatriots Sylvan Primordial, Primeval Titan and Trade Secrets, it creates a gamestate where you get far ahead of other players and like three of the four, you can cheat it out of your graveyard quite early and get virtual turns ahead of your opponents by either drawing more cards, getting more lands, putting your opponents behind and getting more lands and so on
Garruk, Wrath of the Wilds Spellbook Underdark Basilisk Wary Okapi Nessian Hornbeetle Pestilent Wolf Murasa Rootgrazer Sylvan Brushstrider Ferocious Pup Dawntreader Elk Trufflesnout Barkhide Troll Scurrid Colony Territorial Scythecat Garruk's Uprising Dire Wolf Prowler Mosscoat Goriak For a 4-mana planeswalker all of these spellbook options are pretty underwhelming
I started collecting Pokemon as a child and still have my base set unlimited and 1st ed cards if that earns me any street cred