The Grail does not help Viktor in the slightest. Why would giving him some magic resist and 80 AP and Mana on killing someone make him instantly better? It doesn't help any more than simply building those three components seperately in the first place. Hell most of the time you fight AD heavy teams in Dominion, so getting/relying on an MR item is counterproductive.

Edit:
Re: Veigar ~ Veigar is actually decent in Dominion. Not astounding, but decent. I believe a common build for him is tank oriented, using his innate AP acquisition upon kills and raw powerful damage to allow him to build a more durable, support-y build.

TBH, most of those champions need work even in SR since none of them are really used in competitive play in either mode

The only champ we can all at least agree is underpowered is Hecarim.

Fiddle is not bad. He just needs a wing man. I use fiddle alot in dom and he can be very dominate (punt =P

first he can silence a whole team... Fear the biggest threat and if he is build right is very hard to kill on the tower.

where he fails is ganking. you cannot sneak up on a champ solo and kill him. everyone loves crow storm but really its his worst power. it takes forever and its hard to excite correctly, don't rely on it. that was kills most Fiddle players.

stand behind your best damage dealer and go to town. Fiddles can be your mvp.

and build him with some Cool down. do not straight up AP him...

I think this is important to see. As poppy is highly situational in TT and SR but can do amazingly well in Dom. It is the same for Trynd, maybe he shouldn't be as strong in Dominion and situational. I have seen him used as a counterpick for bot and work just fine.

Note: Just to be clear...Viktor is actually not that weak on Dominion. I play him a lot and usually end up 1st on my team. He can out poke anyone, and has great burst.

The only problem Viktor has on dominion is the same one he has on Rift. He has 5 item slots instead of 6. The "upgrade" items just don't cut it for endgame dominion and he ends up being weak as a result when a game goes on that long.

I want 20% CDR built into Dominion Aura to help many of the weaker heroes, unfortunately that will also drive all the OP's into even more OP territory.

^not true, his augments are midgame items and you rarely get a chance to use all 6 slots to their full potential on Dominion.

Viktor is not a horrible champion in the lower elo range, but as you go higher and higher the other champions start to excel better due to stronger team compositions/teamwork, as well as comprehension of builds.

Basically you're playing right now against people who can be played against with anyone.