By Role in the Game: There are three basic roles Pokmon cards (the creatures you battle with), Trainer cards (which give you items, abilities, or effects), and Energy cards (used to power attacks and moves)
Kristen Gregory wrote a great article about how many slots we truly have, detailing how most are gobbled up by the staples that make our decks function
When it dies, if it was a creature, it returns to the battlefield under its owners control as an enchantment alone
White has ended up being the primary of this effect, but blue is secondary, so blue has access when it needs it
Heres a much more exotic U/W deck: Creatures (24) 2 Silumgar Sorcerer 1 Sidisi's Faithful 4 Jace, Vryn's Prodigy 2 Hangarback Walker 4 Reflector Mage 4 Topplegeist 3 Archangel Avacyn 2 Rattlechains 2 Spectral Shepherd Lands (25) Spells (11) This list is a bit too ambitious, in my opinion, but it aspires to set up the Topplegeist + Rattlechains + Spectral Shepherd combo