A spell is modal if it has two or more options in a bulleted list and instructions for a player to choose a number of those options, such as "Choose one" or "Choose one or more." Each of those options is a mode. Spells with spree are modal spells.
Riku of Many Paths
The X in Riku's ability is the number of times you chose a mode for the modal spell you cast, not the number of distinct modes you chose. For example, if you cast a modal spell that allows you to choose the same mode more than once and you choose the same mode three times, X is three and you may choose up to all modes of Riku's ability.
Modal spells printed prior to the Khans of Tarkir™ release didn't use bulleted lists for the modes; these cards have received errata in the Oracle card reference.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Denys Tsiperko
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
