Attribute Substitution and the Defend Action

Which tier of Attribute Substitution is needed to be able to use the substituted attribute for Defend action rolls?

Tier I allows for the substituted attribute to be used for non-attack, non-invocation actions rolls. The Defend action is not considered an attack (See Defend Interrupt Action post). Therefore, is tier I sufficient to use the substituted attribute for Defend action rolls?

For example, a sorcerer has Attribute Substitution I (Presence->Protection). The concept is that his force of personality is so great that he can cause his enemies to hesitate when attacking. Can the sorcerer use his Presence score in place of his Protection score when using the Defend action?

The easiest answer is, ask your GM, in the end it is 100% up to them (especially for you to even use Attribute Sub in the first place).

2nd easiest answer is to just do it the other way. Protection > Presence (unless you want Presence to heal).

The intent behind the tiers of Attribute Sub is that Tier 1 allows you to use it for passive things mostly (HP, Defense) and then doing basic checks out of combat. Per that intent, I would be inclined to say no to using it for Defending with protection.

BTW, there is nothing stopping you from using your Presence to do a Defend Interrupt.