[quote=@EthTenshi]
Illumi ring is useless to Sinys, red seems okay to a degree. Although green seems to work well, but i believe he will learn something similar later? So if he doesn't learn such a thing I'm liking green more. Otherwise red is smartest choice. 

[@Fallenreaper]

But inbetween sento and may? 
[/quote]

Another thing you might want to consider, using a ring prevents him from using Mage Blood. You use runes, it has its own source rather than tap into yours and so won't cause you sickness.