Some spells continue to have an effect over several turns. Such a card is said to "remain in play" once it has been cast. A card which remains in play is placed face up next to the target, or next to the wizard, so that it can be seen. In the case of some of these spells the card itself acts as a marker, others are supplied with separate markers or templates to use instead. If players prefer not to litter the table with cards, then spells that remain in play may be placed face up at the table edge, on a side table, or on any convenient surface where they can be seen by both players.

If the spell has an effect which applies in each subsequent magic phase, then work out the result at the beginning of each following magic phase after the magic cards have been dealt out but before spell casting begins. This applies to spells like the Amethyst Magic spell The Purple Sun of Xereus, the Dark Magic spell Malediction of Nagash and the Bright Magic spell Conflagration of Doom which require dice rolls to determine their effects in following turns.

While a card remains in play the spell cannot be cast again. In most cases the spell will continue to last unless it is dispelled or until the original caster chooses to end it, although the caster cannot always choose to end a spell he has cast. The Purple Sun of Xereus, for example, can only be ended by a successful Dispel.

In general, spells are also ended if they move off the table or if their victims are destroyed or escape, as in the Crystal Charioteer, for example. Most spells also end if their caster is slain but some, like the Bright Magic spell Conflagration of Doom, continue regardless. Where a caster is allowed to end a spell he has cast in a previous magic phase, he removes the card from the table when it is his turn in the magic phase, effectively dispelling the spell voluntarily. The spell card is returned to the wizard, but cannot be used until the following magic phase exactly as if it had been dispelled. A wizard can never cast a spell and decide to end it during the same magic phase.