What is Arlina up to? Page 75 will reveal all.
Taddin is used to hanging around Elves and is surprised to see Arlina disappear. However, all Eladrin have the ability to fay Step. Basically, they move into the fay world for a second and move 25 feet in any direction, bypassing any obstacles in the way.
FYI, in the third panel Taddin used an interrupt ability to block the attack on Arlina.