Sounds good! I just read up on the Ynnari real quick so if I get anything wrong on the character sheet lmk. Going for a kind of Eldar extremist. 

Would it be possible for my character to lead a faction of scourges and drukhari converts? They could reside on Yonah already, perhaps having come to the world seeking alliance with the Exodites or sheltering there from other Drukhari. 

Or they could be fleet based. Whichever works for you. 

In terms of scales for factions are we doing hard numbers? Or just general estimates