ixion
I don't have 6d or 16d so I only have the first letter of 15ac.
This is what I have:
Change the 't' at end of heat to a 'd' (could be 's' but makes no difference.)
Split is at HE//AD (or AS)
Some of 'his' records were perhaps criminal but lots were great!
Also think Tolkien.
This could well be rubbish - if you have 6d and/or 16d and this fits perhaps you could let me know.
Cheers.