I think a really great mod would be the following.
Firstly, it would be a mod which is multiplayer.
Secondly, it would be a mod with a specific game-mode for itself, like Invasion or Persistent World.
Thirdly, it would feature the ability to command bots, and have a maximum limit of 1,000 bots at a time(for the sake of possibilities).
Fourthly(this is the main feature), the game-mode would be similar to Team Death Match.
But it is reversed, as instead there are troop tickets, similar to Strategus battles, where each death takes away from the score of a team. When a team runs out of reinforcements, it loses. Both teams are given a set amount of gold, which can be both handicapped or equal. Also, reinforcements/tickets should be changeable/able to be handicapped in addition.
The gold is used to buy equipment for your team's men. Weapons could be picked up from previous rounds to be used again, in other words making battlefield looting possible.
There should be a time limit of one minute for each team to prepare their troops by buying equipment, and during which, battle can be commenced sooner by all players pressing a 'ready' button.
Fifthly, as an additional feature, it would be nice to have the ability to place scene objects in the time before the round starts, with certain rule applying of course, to prevent abuse. It would allow the players to choose their spawns, and to make fortifications.