I looked at the tournament for about 5 seconds, and saw that doublelift was playing ad gragas....I was wondering if this is viable, and if so what items would you build?

gimicky since his abilities are such that make him an AP caster.

Idk man. When I first started playing Gragas I was shocked to see how high his base physical damage is. It gets even higher when he channels W. Personally I see it as being pretty viable, especially since he has a gap closer/slow and a knockback ult. No idea what items would be good, but I'd think frozen mallet for sure.

Haven't tried it in awhile, certainly not in Dominion, but I recall it being a legit build in SR some time ago.

You could try Rylai's Scepter+Entropy+Atma's+Odyn's Veil? Makes you beefy, gives you a hefty chunk of AD, and you have the slow component with both barrels and auto attacks.

Just throwing out some ideas mainly. It's a 13k-ish build depending on your boots. With those items I mentioned and no runes/masteries, at level 18 you will get 3131 hp, 112 armor, 80 mr, 319 AD (70 included from W), and 80 AP.

Used to be pretty popular on TT.

I'd imagine a Malletmogs would be good.

The meta on SR has moved past AD Gragas, but I could see it being viable on Dominion.