While active, all spells cast will have zero casting time, other than the casting animation. This applies even for spells that aren't normally available to Red Mage, such as Ninjutsu, if utilizing a Ninja subjob. However, spells still cannot be cast non-stop: there is an approximate 2.5-3 second delay after casting a spell before the player is able to start casting another one, and Chainspell still does not remove that delay.
All spells cast while this ability is active will have their recast timers reduced to zero as well, meaning that the same spell can be immediately cast again if so desired and if MP permits (following the natural delay between spells). However, the activation of Chainspell does not cause any spells that are already recharging to immediately become available.
MP costs of spells used while under Chainspell's effect are not reduced or affected in any other way. Due to the likely high amounts of spells cast in a short period of time, the Red Mage must ensure that he or she has sufficient MP to cast everything intended when engaging the ability.
The rate at which consecutive spells can be cast is also hindered slightly by the previous spell's animation.