While some longtime Magic players feel that adding characters from intellectual properties outside of Magic: The Gathering detracts from their ability to immerse themself in the game, its hard to argue with results, and The Lord of the Rings: Tales from Middle-earth reigns as Magics bestselling expansion set of all time
As if that wasnt enough, every time you cast a spell with X generic mana in its mana cost or activate an ability with X in its activation cost, you copy it and choose new targets
It makes it easy and possible to go wide with Human tokens, taking advantage of several of the cards in the deck to make that token army overwhelmingly strong
You could write entire best-of articles for constructs, equipment, mana rocks, myr, thopters, and so on (and we have!), so check those out for more comprehensive lists of those individual types of cards
when you build your deck, you circle two of them and can then add one colour of either mana to your mana pool