hmpfrr, lets see.
You will have a map with a small arena.
This arena is surrounded by walls or cliffs so units can not walk out of it.
At cliffs/walls should be an option to CREATE units.
Well if u have that area u can start.
Each player starts with the same unit and the same hp/mana.
EACH new level/game gives the unit a random spell. (blink, divine shield, evasion, ..) Anything that could help the protection against attacks or the game. (Make sure u balanced it).
Each new game spawns (random) units on the cliff, which will fire are random directions.
U can make it a mortar, catapult, demolisher, ...
Another option is to spawn HH with it that are just throwing spears randomly into the area or grypon ryder (hammer hit = jump), ... U can find alot of variations.
Another idea is when a game is started again, a ball will appear and will bounce from everything it hits, making the one who took the hit to take damage.
Make a leaderboard which shows then wins of each round that has been made.
The host should be able to pick how much rounds.
The winner should be the last man standing.
More?