Well, here's my take on the multiplayer variant.
You're gonna need several sets of markers (or cheap beads). 1 set for each race in the game (or 1 for each player).
I've seen wytefang's variant on bgg and was thinking about the problem of getting a burn token stolen and holding of attacks until you are sure to make a burn.
If instead of the original dmg markers you use custom markers for each player/race you could track down each dmg point done to each capital zone. The rules go like this:
Original rules apply all the same. But each dmg you apply gets marked with your own custom markers.
You try to burn other players' zones as usual and mark the dmg you apply with your markers. Once the zone burns, and only when it burns, the dmg markers on that zone become victory points and are given back to the players that applied them. So... each player gets their respective dmg markers back as points once the zone burns.
Give 2 extra poins to the players that actually applies the burning dmg, as a bonus for "realeasing" the points.
A zone with developments gets more hit points, so more dmg can be applyed, but if the development is destroyed and the zone burns because of this... the points get returned to theis owners without any bonus.
If a player burns his own zone he also does not get extra points.
Moving dmg from zones works the same as the original rules, but the moving player gets to choose which marker gets moved, if there are markers from different players. Once a zone burns only the dmg on it gets returned as points. The same applies for healing dmg... the healer chooses which marker to remove.
Burned zones cant get more dmg as usual.
Player that gets 25 (3 players) victory points wins. Add 10 more points for each additional player (10 points is the amount you'll get for completely burning a zone + the bonus for burning it). I choose 25 because its the points for 2 complete zones + some extra hit points players might add with developments.
Ganging up on weak player might happend, but he wont be able to provide a full win for either player, even if he gets his 3 zones burned (30 points split to the stronger players), so the stronger players will have to burn each other zones to recieve their points back and win the game.
Edit: If when a zone burns, 2 or more players end up with more than the winning number of points at the same time, the one with more points wins. If 2 or more players end up with the same nunber of points, you can call it a tie or decide based on who has more power on the table at that point, or more units...
Thats my best shot so far... The game remains completely the same, the only diference is that after a zone burns the dmg markers become points.
The number of points might need tweeking and i need to playtest it more, but i think this is ok. What do you guys think?