Im not sure how I feel about Senna yet. Im still playing around w her on PBE. But right now it seems like the only way to build her is AD / Lethality.
Could we have an option to focus her on Shield/Heal Power or AP?
I think it would add a lot of build diversity to her, if you offer the ability to play her as a more defensive support. Just give her some better AP scaling on her heal and shield, and maybe some AP movement scaling for her mist form, or AP duration scaling on her root duration.
This way, you could offer Senna the choice between damage or utility, light or dark (Instead of 90% dark and 10% light)