New Advantage: Blood of the Gods

[Arvernian]

I'm working on a fantasy setting where priests gain their powers (in this case power investiture) by drinking the blood of a living demigod. I've modeled the ability (from the perspective of the "deity") like so.

The Fluff:

A mortal who wishes to serve one of eight powerful immortals in control of a gigantic urban complex approaches the being in question and swears an oath after which he drinks the demigod's blood and receives the ability through his connection to channel mana into the form of spells. The downside is that for as long as the Power Investiture lasts, the mortal must obey the demigod's commands without question.

The Crunch:

Blood of the Gods: 270 pts.

Affliction 3 (HT-2, Advantage (Power Investiture), Cumulative [+500%], Blood Agent [-40%], Extended Duration (Permanent) [+150%], Link [+10%]

Affliction 3 (HT-2, Disadvantage (Reprogrammable) [+10%], Accessibility (only has to follow orders from one sorcerer king) [-40%], Blood Agent [-40%], Extended Duration (Permanent) [+150%], Link [+10%]

My questions are as follows:

1) Is the math right?

2) Are all of the traits used correctly (can I use Blood Agent 2x to limit both linked attacks or does it apply only once to the whole package?).

3)Is there a more efficient way to do this that will cost fewer points? I should note that I want to keep the two traits linked rather than having them as multiple effects of the same Affliction since that allows a character to particularly gain the bonus without taking the penalty (thus allowing a cleric to turn against his god, an important plot point).

4) Does this seem reasonably balanced for the point cost?

Any input is appreciated.