They can't try to remove the card from your graveyard to stop you from paying the cost
Cycling from the battlefield, also known as cycling from play, first showed up in Urzas Destiny on a handful of permanents
Most events with an entry fee give you some gems as reward not all, though, so make sure to check the reward track (in some rare cases you only get gold, packs, and/or cosmetics, but not gems
Admittedly, Treasonous Ogre is more powerful in many scenarios, especially in the early game, but Mana Geyser comes with no risks or strings attached
For those that have been under a rock for a while, most Burn decks nowadays stretch to fully embrace green for the Kird Ape upgrade in Wild Nacatl, and the Skullcrack upgrade in Atarka's Command
Instead, it will greatly slow your opponents down, requiring them to spend at least 10 turns to take you out