[Nantuko Joe]

As soon as he does it, it covers the entire area. Play SFIII and find out. Also, its range is unlimited because it is energy expanding, and it carries some beam properties like that.

Okay, I got this figured out now...

Gill, being a deity, will prolly want to see what Goku's Kamehameha is (or not, and may or may not begin the battle with the Seraph). Goku begins charging the Kamehameha, and Gill unleashes the Seraph Wing. As his barrier expands, Goku Shunkan Idous inside the barrier, away from harm, and behind Gill to finish off his Warp kamehameha. The Kamehameha destroys (or cripples) Gill's current body, allowing for his destruction at the hands of anybody, really.

And no matter what, if Gill's Seraph Wing expands in ALL directions, then it also kills off the weaker DBZ characters and the weaker SF characters. Then the energy of the Seraph wing, since it continues to expand in all directions with unlimited range, kills everybody on earth and prolly destroys the earth itself. Without earth, there's no atmosphere. Without atmosphere, the body cannot survive. Gill's body dies, and the fight ends in a draw.