There are some awesome activated abilities out there but getting one of them into the graveyard and getting a four-drop onto the table is remarkably similar in difficulty level to getting the creature into the graveyard and then putting it into play
// Starfall - Whenever The Lord Master of Hell attacks, it deals X damage to each opponent, where X is the number of noncreature, nonland cards in your graveyard
If you're running lots of eldrazi scion generators -- which I recommend -- then Deepfathom Skulker is really amazing, as are other Coastal Piracy variants like Bident of Thassa and HOLY CRAP SO GOOD Kindred Discovery
6 Wurmquake If you have a ton of extra mana lying around, Wurmquake can be a great sink for all those spare resources
This is the inspiration for the Unglued card, Chaos Confetti
Oh wait, this guy's not playable never mind