Unblinking Observer
{1}{U}
Creature — Homunculus
Oracle Text
{T}: Add {U}. Spend this mana only to pay a disturb cost or cast an instant or sorcery spell.
Watch Out
Mana abilities don't use the stackRules Note
If this card's activated ability produces mana and doesn't target, it's a mana ability. Mana abilities resolve immediately without using the stack — opponents can't respond to them. However, abilities that target (even if they produce mana) aren't mana abilities.