I did not even think of using Rebuttel with AotH, even though I am the one who normally cast it.
I currently have Adaptive, Efficient (reduces Vis cost to 1 per 10 levels), Flexible [Size +1] (Each Flexible adds a single change to R/T/D that you can make while casting the spell, it does modify the level), and Penetration. I do believe we have a quality 10 book on AotH Spell Mastery I have not read yet (it would net me 26 XP, enough for Mastery 5) so I will talk to my group about if they feel Rebuttel will work with it.
Which leads into the problem for me in this thread, in which I several of what I consider "cool" combinations which use some of our HR Spell Mastery abilities.
Hummm, another group of spells I have is variants of Maintaining the Demanding Spell (in addition to the normal version, I have a R/C and Sun version) with the non-R/C versions having Fast and Multi (along with Adaptive and Secure, which further reduces Botch dice). They are useful to "tie-off" spells (especially Spont spells), extending their duration. Because they are Fast and Multi, you can convert over many spells very quickly.
"Ceremonial Mastery on the Leap of Homecoming"
For use in getting into places you really shouldn't be?