The last message dates back to 2011. Is the mod still being worked on, or is it dead? The idea is actually very appealing.

Work on the mod is ongoing, but the main discussions take place on the heroes.ag.ru forums. Currently, the mod is close to releasing the tactical mode (duel presets). The release will be published on this forum as well (heroesworld).

Added 7 minutes later
Just in case, I'll post links to the pre-release version for review:
WGE-Duel8Beta
Info
This version contains almost finished creatures from all 8 factions (with the exception of some details that may be changed, especially the spell set for Warlocks).