Gaming devices and methods of operating gaming devices are provided. In an embodiment, a single activation of a gaming device can cause a series of outcomes including a symbol cascading effect upon the occurrence of sequential triggering events. In an embodiment, the triggering event occurs when a predetermined combination of symbols is generated and displayed in associated symbol positions, and a designated symbol is generated and displayed in at least one symbol position. If the triggering event occurs, the outcome can include fixing or locking the designated symbol in the symbol position and replacing each of the symbols in the combination of symbols with a generated symbol. Awards are provided for each winning combination, and an incremented modifier is applied to the awards for the occurrence of at least one triggering event. The likelihood that the triggering event will occur increases with each designated symbol fixed in a symbol position.