Immediate actions while concentrating??

[shaga]

The title says it all. Can you use immediate actions while concentrating on another spell? What about when you are casting a 1 round casting time spell?

[Psyren]

You can, so long as that immediate action is not itself a spell. The general rule is that you can only cast one spell at a time.

Rules quotes:


To cast a spell, you must be able to speak (if the spell has a verbal component), gesture (if it has a somatic component), and manipulate the material components or focus (if any). Additionally, you must concentrate to cast a spell.


To cast a spell, you must concentrate.

These lead us to:


You can’t cast a spell while concentrating on another one.


Combining an immediate with a full-round spell is just fine, so long as the full-round spell is fully cast before or after the immediate action one.