Elvish Warmaster is a fantastic inclusion for pretty much any elf deck due to going wide and providing an outlet for all that mana produced by Circle of Dreams Druid and whatnot
15 Mental Misstep Banned in Modern & Legacy, Restricted in Vintage, Legal in Commander The New Phyrexia set was packed with jaw-dropping cards, from Karn Liberated to Elesh Norn, Grand Cenobite to Batterskull
That means the higher end stuff can get tossed out a lot, and you want to make sure you have everything from the hilarious Scornful Egotist to powerful Green tramplers
Combine this with goblin tokens and a card like Rundvelt Hordemaster, and you can cast a good chunk of your deck
Plus, it doesn't remove itself from the game so you can get it back with Regrowth, Yawgmoth's Will, and other graveyard recursion cards (including Gaea's Blessing, further down on this list)