Eye of Ugin

Zendikar Expeditions
Colorless Eldrazi spells you cast cost less to cast. , T: Search your library for a colorless creature card, reveal it, and put it into your hand. Then shuffle your library.
Legal in: Commander, Duel, Legacy, Vintage
Banned in: Modern
2010-03-01: Eye of Ugin doesn’t have a mana ability.

2010-03-01: Eye of Ugin’s second ability lets you find any colorless creature card in your deck, such as an artifact creature card that has no colored mana symbols in its mana cost, or a creature card that’s become colorless due to Mycosynth Lattice.

2013-04-15: Mistform Ultimus and creatures with changeling are Eldrazi. If they become colorless, possibly due to Mycosynth Lattice, Eye of Ugin would reduce the cost to cast them by .