Okay, i've read a lot of threads about kakashi vs... and some of you keep as an argument that if somebody gets warped to the kamui's dimension, he can be saved making a reverse summoning or watever.
A summoning is traveling at the speed of lifght, no more than that, so if Deva Pain (for example) gets warped in the kamui's dimension, and the animal path wants to summon him back, he can't, because that's a travel at the speed of light, it can't make a dimensional barrier, si if you get trapped with kamui, the only way out is KAMUI.
Get that sulg princess tsunade?
If kakashi warps tsunade, she can't go back with a reverse summon, because she needs a black hole to go out that dimension,and the speed of light is no black hole.