Once in play the persist ability lets the Shepherd sit as insurance against wrath effects for all the non-persist creatures you might have, or any that already used their persist ability once
The difference between 12 mana and 10 mana for Ulamog, the Ceaseless Hunger, even for Tron decks in Modern, is huge
Without some sort of answer to Avacyn however, your opponents will be facing down your indestructible board state
How To Play The Deck The Lord of Pain is all about sowing chaos and sending burn damage to all your opponents
Notable, daybound/nightbound werewolves do not transform as the result of an activated/triggered ability, and their transformations at the start of a turn cannot be responded to
[Card]Smugglers Copter[/Card] rounds things out nicely as a way to filter through redundant legends and excess mana while fueling delirium along the way