Thank you everyone! I didn't even spot the whole regenerating Devoted Druid as an additional infinite mana source also! That's pretty awesome!
As for the Lead the Stampede, I run them in the mainboard and they are definitely better than Nissa because they save you from Thoughtseize and IoQ which are staples in a lot of the decks that run black. It's a card that allows you to keep tempo even if they are able to wrath.
It's not the regenerating ability from Ezuri, it's Ezuri's +3/+3 that allows 2xDevoted Druids to continue growing in size and continue generating infinite mana in the process.