I've recently built a blue/black zombie deck and for kicks I put a {Ghoultree} into it and I've got a few {Transguild Promenade} and a {Rooftop Storm} in this deck. But is it okay to have a card that isn't one of your basic land types in your deck? This is the first time I've done this, so I'm curious. Thanks for the help!
Yes lol
Unless you're playing edh format, you can put whatever colors you want in your deck! You'll find that a lot of reanimator decks run only swamps, but have creatures of all colors in them, because they don't need the mana for those creatures, they just need the mana for the reanimation spell.