There are a few things that are should be included in your commander deck
From Llanowar Elves to Scuttlemutt you have tons of dorks that can tap for a mana, and you have some that tap for more than one like Palladium Myr
This is built with squirrel synergies in mind and when paired with a couple of typal buff cards, can get real dangerous
Maleficent, Sorceress), while higher-cost (and rarity) options such as The Queen, Wicked and Vain and Magic Mirror provide strong, recurring mid-game draw support
Mystical Tutor offers the same precision that the best black cards in MTG provide, but is limited to spells
Pramikon, Sky Rampart : In a strategy where avoiding attacks is the goal, being able to completely shut out two players from attacking you is huge