At the beginning of your upkeep, reveal the top card of your library. If it's a land card, put a summoning counter on Tomb of Demon Sealing.
, Remove six summoning counters from Tomb of Demon Sealing and sacrifice it: Put an 8/8 black Greater Demon creature token with flying and trample onto the battlefield.
Created for Challenge # 044. I wanted to create a version of Goblin Bomb that was 1 mana, because that seemed like a great Timmy card to base an entry on. But along the way I found myself making enough changes that this is where I ended up.
The top of library restriction is because people prefer dealing with cards on the top of their library to flipping coins. To Timmy, both feel equally random and this one doesn't need extra equipment. To Johnny, the top of the library is far more easily manipulable. But the Johnny appeal is somewhat incidental to this design.