Search your library for a card and exile it with X time counters, where X is its mana value. If it doesn't have suspend, it gains suspend.

Suspend 1—{U}{R}(Rather than cast this card from your hand, pay {U}{R} and exile it with one time counter on it. At the beginning of your upkeep, remove a time counter. When the last is removed, cast it without paying its mana cost.)