Tower of Glass

{t}: Add one mana of any color the last spell cast
this turn was. Until end of turn, you can't cast
spells that share a type with that spell.
Nobody knows who built these towers on the ice of the
Glass Dunes or what their purpose was. Even from
the farthest horizon, their distant glimmer arrests the
gaze and blurs the mind. Although gigantic, they cast
no shadow. And for those eager to learn about their
secrets, from within a silent whisper echoes endlessly, leading them astray with more ques