Looks to me like Toch doesn't subscribe to the widely held lawyerly belief that you shouldn't put a witness on the stand unless you know exactly what that witness is gonna say.
I'll also remind the jury that the "fateful night" referred to by Lady Mab in her testimony is the night when the Nulla Lucis killed the previous Oberon and Titania and all that: it all starts here if anyone would like to review the transcripts, near the end of Act II of "A Long, Long Trail A-Winding," our 24th storyline.
Thirty - The Way of All Flesh