Here is one of the best solutions to Bloodghast, Death's Shadow, Gravecrawler, and a whole army of tokens. Snapcaster Mage would be a great target for Legion's End as well.
The only drawback of this card is the sorcery speed, which is a bit slow for such an important effect. But even then there is no doubt that Legion's End will save you a ton of games that would've been easily lost if not for this card.
This is obviously a card designed to hit Dredge, and time will show how effective it is against other archetypes. So keeping it in sideboard would be the best idea for now.