Primarily built as a White / Black Enchantment Deck.
This deck is mainly built around the mechanic of Grim Guardian, and is built to play enchantments as many times as possible to trigger his Constellation mechanics to slowly weaken the enemy, while also having some options to make attacks thhat can finish an opponent off. This deck also utilizes some minor graveyard return spells to re-trigger "enter the battlefield" effects, including Grim's Constellation effect.
First off is the Star of the Show: Grim Guardian. His Constellation effect is the main focus of this deck, and his 1/4 Power/Toughness makes him a decent defender and hard to remove without direct destroy or exile effects.
Now to trigger his Constellation, we need a ton of enchantments. Ethereal Armor is perfect for this deck and can lead to some powerful swinging if the opponent lacks proper removal, Corrupted Zendikon can make a 3/3 for only 2 mana, and can help re-trigger the "enter the battlefield' effects of the Piranha Marshs and the Scoured Barrens, and Oblivion Ring can be used for proper removal of almost any permanent. The ring can also trigger an infinite loop, which combined with Grim, can instantly win the game using the Grim Guardian + Oblivion Ring
combo (3 Rings targeting each other in succession with Grim Guardian in play).
Pillory of the Sleepless helps with shutting down opponent's creatures and slowly draining life as well, Angelic Renewal helps flicker creatures, mainly Grim, back into play, and Font of Return can bring back any 3 creatures. The last two also help to re-trigger "enter the battlefield" effects, which every creature in this deck has, besides Hopeful Eidolon. He is mainly in this deck as a 1 mana drop for Grim's Constellation, or a cheap creature to pump up with Ethereal Armor for some great Lifelink swings.
The remaining creatures are here for their "enter the battlefield" effects. Heliod's Pilgrim helps tutor out Auras that might help any given situation, and Auramancer/Monk Idealist can return any enchantments that fall into the graveyard. They can also be used to return Font of Return, and the Font can return them as well, making a nice loop or returning that can also benefit you with a net gain of 2 addition creatures from the graveyard over roughly 2-3 turns, depending on the mana situation.
Cloudshift is also a nice spell to re-trigger those entering effects on the fly for 1 quick damage to their life, one Aura tutor, or one Creature returned to your hand.
Sideboard: Brink of Disaster is used mainly for Land Hate, but could be used as en expensive way to shutdown more creatures, if the O-Rings and Pillory aren't enough. Mainly Land Hate though.
Disenchant is a great choice for Enchantment and Artifact Hate.
Nihil Spellbomb can nuke graveyards in case anyone else tries playing from the grave, with the added bonus of drawing as well.
Trespasser's Curse can slow down Jund/Aggro Decks, or make them pay for playing aggressively. Also, it has that Enchantment Synergy with Grim, the Mancers/Idealists, and tutorable with Heliod's Emissary.
Unmake makes for good creature removal when O-Rings aren't enough.
