Prismlands

Ethereal Cloud: You may play an unlimited
number of Basic Lands during your turn.
{t} : Add one mana of any color to your mana
pool. ({u}{b}{r}{g}{w})
The lands lay bathed in clouds of all colors, fogs and
mists of more hues than the eyes could take in. Every energy imaginable seemed to converge here, power
and color coalescing as one.