**Staff of Defense** class feature:

> 
> ...once per encounter as an immediate
> interrupt, you gain a bonus to defense
> against one attack equal to your
> Constitution modifier. You can
> declare the bonus after the Dungeon
> Master has already told you the
> damage.
> 
> 
> 

**Shield** Wizard Utility 2:

> 
> Immediate Interrupt Personal
> 
> 
> Tigger: You are hit by an attack
> 
> 
> Effect: You gain a +4 power bonues to AC and
> Reflex defense until the end of your
> next turn.
> 
> 
> 

Could you activate these powers against the same triggering attack and thus stack them against the same attack?