Updated the original post to include several ideas and add a map including brush and swamp.

I'd suggest some thick walls around the flag area so you don't just get the Shaco sneaking past the team fight, grabbing the flag, then instantly hopping over the wall to get away with it.

Also, global ults would have to be stopped with the flag, because then you just have Pantheon, Twisted Fate, or Shen just booking it to the middle, then ulting right on out. But I also feel like that might ruin a good character.

As for what I said about TT buffs, the dragon there gives a 12% damage buff to all team mates, there's a movespeed camp and some other one. And I think moving some closer to the middle would be better. I doubt anyone will want to go that far into the other team's base to steal a major buff. I might nudge them a little closer to the flag point.

Here's just another question. About how large is the flag area? In terms of comparable Rift areas. Because if it's too small, turtle characters would have a field day. I would run a Shaco, Teemo and Heimerdinger. Have boxes, turrets and mushrooms flooding the area. Defensive play would seem to be really common to me if I were playing this map.

This would be so sick.

To address this problem I would like to reply with my previous idea. when I champion picks up the flag they should lose the option to use their abilities. maybe still be able to use their summoner spells but they should not be able to use their personal spell. just my opinion

"edit" also I was thinking a smaller number of nutral (sp) minion camps. maybe 10 to 12 max on each side cause that about doubles SR minion camps and would make it easy to support double junglers. but three junglers would be under farmed

"edit2" also there should be 4 entrances to the main base. I was thinking two lanes but they divide into two entrances. and you could have maybe 4 minions a wave go down each making a total of 8 per lane. just a thought. that should create some variety and options to the mapl.

@TeknoWizard (and Lasie cause he got here before me)
The Map: You brought up 3 things about the map structure that I agree with (apparent flag arena size, jungle placement/size, base entrances) and that combined with the swamp area I want to add makes me want to redraw the map to fix all that. That being said, I'll be busy all weekend (starting after this post) so it will take a while to get started on that.
Abilities and the Flag: It seems like the only game-breaking abilities for the flag bearer are ultimates, and on further thought it seems like a large number of ultimates could be game-breaking, but I can't think of a regular ability that would be, so I think restricting ults while holding the flag is fine, but let them keep the rest of their abilities. Thoughts?
Buffs: I like the sound of the TT buffs, so I'll look into them more on the wiki page. Maybe crossing them with the SR buffs to give a benefit to laners too? I know how APs will always love their blues.

It's only been a few days, but the feedback I'm getting is phenomenal, and it's all thanks to you guys. I'll be off camping for the whole weekend, so I would greatly appreciate if anyone with ideas of any kind, even just giving your opinion on other people's ideas, would help keep this thread bumped until I come back.

Nice job.

This is a great concept an design. TBH it makes the idea of dominion and it's map kinda boring.

On the subject of abilities: Issues with Ults such as Pantheons: Make a field around the flag area that doesn't allow teleportation. This will include the summoner spell teleport. In order to balance out the game, either all or half a team's ults should also be inactive in the flag area.

Issues with flash-type abilities going through walls:

Make the wall too thick to flash through. Just that. Safest way of not nerfing any ability from any champ.

I like the idea of having 6 champs, instead of buffed like they are in dominion, they're "nerfed" in a way. should allow for more creative CC strong team comps with actual skill required rather than the current tiresome meta.

I think that some walls should still be able to be "flashed" over with some abilities. that way ez shaco and those such wont be completly hindered and would also encourage the use of wards

Exactly. But I was just saying the walls directly surrounding the flag area should be too thick to flash through. Once they get out of the cluster-#%&* going on in the middle, then they should be able to jump through the wall. But as I originally said, a Shaco or Shen would just run right through the team fight, then hop over a wall with the flag.

And then I just had another idea. The flag would need to reset after like a minute of being dropped. Because a winning team that just wants to farm kills would just take the flag to their base, but drop it right outside. Then they would just camp the other base for kills. Yes, this would happen. We all know the players that will ignore taking down the Nexus because the enemy Sivir is at half health. After some time, it would need a reset.

I had another idea with minions reaching the ends of lanes too. Maybe, since most people will be going for the flag/farming the jungle, that when the reach the end, they just disappear, but give a small gold bonus to the whole team. If you make it 20 gold per minion, and you shove the lane to get them through, that can make a HUGE bonus and actually draw some attention to the lanes. Because right now, they seem pointless. Or maybe add points for it. At every 5 minions to the end of a lane, you get a point.