Even conventional draft decks can make use of this Elf creature, such as cards that make Roles, although that may be too slow and sporadic for some players' tastes
Another thing the Swamp King appreciates is a player casting black spells, which means well want a high volume of black spells in the deck
If all of their blockers commit to one of your creatures, by my estimation, your other creatures aren't getting blocked
It only works well in decks that discard plenty of cards and have other cards that work well from the graveyard
The prolific price rise, and particularly the recent spike, may well have something to do with the upcoming The Hobbit set, releasing in August (check the MTG release schedule here)
Screamer-killer will zap stuff whenever you play a big creature, which this deck likes