The End Four mana to exile a creature or planeswalker isnt a good deal, but its not the end of the world either
For example, Juri, Master of the Revue grows when sacrificing other things, but it also essentially gives you an extra Fling when you sacrifice it
Luckily, since Revavroom is such a new addition to the Pokemon TCG, you should be able to find all of its cards in near-mint (NM) condition
Depending on the curve you're running there's also Hibernation's End to help smooth things out in the early game, and Mana Reflection with Moment's Peace to help lead you to the end game
Commander Sefris of the Hidden Ways Whenever one or more creature cards are put into your graveyard from anywhere, venture into the dungeon
The grading standards were designed with really old tobacco cards in mind