As far as i know there is no way to get 2 rolls per attack for more than 1 round.
They didnt nerf the Half Elf tiwn striking avenger with 4 rolls per Standard Action ?
Whats the biggest damage weapon you can use with this combo ?
Any melee weapon you want really. Mordenkrad, Executioner's Axe and Fullblade are the popular ones.
Can't you take Warrior of the Wild and dual-wield waraxes?I believe Ishtar is talking about Twin Strike as the Dilettante power (which can be at will come paragon).
The biggest [W] you could do is the Waraxe (AV) with a d12 for damage (which, and I don't have any experience with Avengers mind you, but the extra damage may be better than the +1 prof of heavy blades), but as for your off hand, the best you're looking at is a d6 I think. A Double axe may be a better choice, it still can be used as a two handed weapon and has d10).
You would hope it would be high on their list. They could say that the Avenger feature only works on Avenger attacks, paragon path attacks and MBAs.