Possible errors here are Mods, EnhancedBlood and AmnesiaShrine were at least once faulty, the latter was possibly revised?
To my knowledge SkyrimFloraOveraul is a Skyrim-Mod and would change (possibly destroy?) the alchemy of Enderal.
I don't know what changes Bards now. Mods are not supported by us.
Even without mods you can't use your savegame in the arena, it is damaged or a bug,
do you still have a savegame before your first visit to the arena? (or before your first visit to the Undercity?)
Could you upload such a savegame?
You can find it in ...\Documents\My Games\Enderal\Save, we need the -.skse and the -.ess- file of a manual save (no quick- or auto- save).
Please put them in a rar or zip archive, as skse cannot be used directly in the forum, and add them to a post here, we'll look at them then.