A bound spell is cast just like an ordinary spell – using dice from the power pool (the model may do so even if it is not a Wizard). The required casting value is equal to the bound spell's power level.
Whenever you attempt to cast a Bound Spell from a Magic Item (but not 'innate' Bound Spells), you may add one free Power dice to the casting roll, representing the magic power held within. Note that you must always use at least one dice from the power pool when casting bound spells. You may use a maximum of three dice when casting bounds spells (including the free dice mentioned above).
Bound spells never benefit from any casting modifiers that the user might have. On the other hand, failing to cast a bound spell does not break a wizard's concentration, as using an item that contains a bound spell normally would not require anything more complex than uttering a single word of activation.
Bound spells are often tied into a spell from a magic lore. Where this is the case and there is a choice of casting levels, the bound spell is always the easier 'unboosted' version with the lower casting level.
If a bound spell is from a Lore of Magic with a lore attribute, the successful casting of the bound spell will also trigger the lore attribute. It is worth noting that some lore attributes effects target the Wizard casting the spell. In the case of Bound Spells it will target whoever is casting the spell instead.