Army of the Drowned (Valyrian) reads:

Character, Greyjoy, cost 5, STR 5, Military Power
No attachments.
Response: kneel 1 influence to save Army of the Drowned from being killed or discarded. If Army of the Drowned has already been saved this phase, it claims 3 power.

Let's say someone with 6 STR and Deadly attacks me (military), and I have Army of the Drowned available. I defend with Army of the Drowned.

I lose the challenge, and kill Army of the Drowned to satisfy claim ... and kneel 1 influence to save him. (so far, so good?)

Then I also choose Army of the Drowned to satisfy Deadly, kneel another 1 influence to save him ... and it also gains 3 power. (wow!!??!!)

Is that right?

Stormtower said:

Sure, but someone probably wouldn't attack into you with a Deadly character when you had the army and two influence standing unless he/she had some other nasty effect that he/she wanted to trigger.

There is a nice combo with the army, Theon Greyjoy from Five Kings and the event My Life for Conquest.

With just 6 1-influence location you gain 15 power in marshalling.