Let me start off by saying that I am posting this build under the opinion that
1. Bloodlines don't count for ECL
Tiefling Conjurer 1/ Fiendish Bloodline 3/ Master Specialist 1/ Malconvoker 1/
Incantatrix 3/ Malconvoker 4/ Master Specialist 9/ Something 1
C.O. conventions dating back to '05 have bloodline
levels count as a normal character level. More recently
PLZ has pointed out they are LAs and can be bought off.
There's an LA+0 Tiefling.
If you do it this way with LA Buy-off, you'll be ~mid 19th
level with no LA. You won't need that "something 1".