It's kinda a C# dim stuck on top of an F# dim. Arranged around a bit, I guess an Edim7 (E,G,Bb, Db) with an added m6 and 9th (C and F#) - Edim7m6/9, I guess, if you had to call it something.
The F# dim at the bottom is a good substitution for a B7 chord (it inverts to a Cdim7, which is essentially a B7 with the root moved up a half step, suggesting a B7b9 if you arpeggiate it over a B in the bass), so it could be used as that, with some rather tense upper extensions. Is this what you do with it? The C#dim at the top is a good substitution for an A7 (it inverts to a Bbdim7, which is essentially an A7b9), but with the F#dim in the bass you've got some VERY tense half-step intervals present - C and C# (major and minor 3rds), Bb and A (b9 and implied root)... Youd be looking at something like an A7b9#9 (as the m3 would have to be described as a 9th, not a 3rd), which is just a harmonic mess. It might work, but I'd want to hear it.
You use this over the B, then, in an E blues, right?