It might be an interesting idea to have two Alchemy cards like the following:

Cost: WUBRG (CMC=5)
Legendary Enchantment
Legendary creatures you control get +X/X where X is that creature's manavalue.
Whenever a creature with no ability enters the battlefield under your control put the following conters on it, a vigilance counter if it is white, a hexproof counter if it is blue, a lifelink counter if it is black, a trample counter if it is red and a reach counter if it is green.

Cost: WUBRG (CMC=5)
Legendary Artifact
3,tap: Draft a card from its spellbook. If it is a creature, put it onto the battlefield. Activate as sorcery
|spellbook contains: Barktooth Warbeard; Isamaru, Hound of Konda; Jasmine Boreal; Jedit Ojanen; Jerrard of the Closed Fist; Kasimir the Lone Wolf; Lady Orca; Sir Shandlar of Eberyn; Sivitri Scarzam; The Lady of the Mountain; Tobias Andrion; Torsten Von Ursus; Yargle, Glutton of Urborg; and at last the firstly mentioned card