his ultimate Shield........the Susanoo...and u can see the another shield which his susano is holding its the Yata Mirror which is the greatest shield of all.........bcz no attacks can penetrate yata mirror ...which make him invincible..........
Touma Kamijou's Imagine breaker and Accelerator's Vector shield from To aru majutsu no index/To aru kagaku no railgun are 2 of the best shields I can think of
~The Imagine breaker (Touma's right hand) can negate and destroy any type of Supernatural ability like magic powers hoặc the like within contact.... Alot of people think if they cut his right arm off it'll make him useless but nope, cutting his arm would just make it stronger, even making it spread through out his whole body and unleashing the power behind the imagine breaker XD
~Accelerator's vector shield is an AIM (An involuntary movement) its like an aura his body emits which reflects everything (and bởi everything, I mean everything!) back before it even comes in contact with him through vector change. This skill is involuntary so it acts automatically basically that's why he has an albino look because his vector shield even deflects UV rays from the sun
