There's nothing stopping characters casting spells on a character who's on the Coc, assuming the parameters of the spell are satisfied.
You can even use an adventure card that allows you to summon someone to you such as "the Arena" on the character on the CoC.
You mean Arena that says:
"You may summon 1 character in this Region to fight."
How you get the Arena to the Inner Region is an interesting dilemma. Gong of War on the other hand is a valid method for removing a character on the CoC.
Ah yes, good point.
I guess the point I was trying to make is the character on the CoC can have spells cast on him and generally be affected, assuming it falls within the parameters of the spell or ability.
I shouldn't have used the Arena as an example tho, as that doesn't fall within it;s parameters.
I didn't actually have my Talisman game to hand tho to check the specifics of that card, but it was the first thing that came to mind.