Profane Tutor

The mana value of a spell cast without paying its mana cost is determined by its mana cost, even though that cost wasn't paid.

Due to a recent rules change to suspend, you are no longer required to cast the suspended card as the second triggered ability of suspend resolves. Instead, as the second triggered ability resolves, you may cast the card. Timing permissions based on the card's type are ignored. If you don't cast the card, it remains exiled with no time counters on it, and it's no longer suspended.

If a card with no mana cost is given an alternative cost equal to its mana cost (by Snapcaster Mage, for example), that cost cannot be paid and the card cannot be cast this way.