Ffa (default): Everyone against each other.
Teams (-teams): Prechosen teams. (This is also the way you set observers in Warlock)
Shuffle (-sh): Shuffles teams randomly every round. Will randomly switch between big and small teams.
Shuffle min (-sh min): Shuffles teams randomly every round. Will always make the smallest teams possible.
Shuffle max (-sh max): Shuffles teams randomly every round. Will always make the biggest teams possible.
King (-kg): Shuffles teams randomly every round. One player from each team will be king, who takes 10% less damage and can heal with their scourge. If king dies, the opposing team gets healed. Will always make the biggest team possible (I think).
Pretty sure you can also do Team King, with the first player in each team always being the king. I'm not able to test it right now, but the command would be (-teams + -kg).
Avatar (-av): One player starts as avatar in first round. He gets additional HP depending on amount of people playing and his spells do more damage/knockabck. Rest of the players must kill the Avatar or damage him as much as possible. In this mode, you get points purely for damage. The player doing most damage will be avatar next.
Deathmatch ffa (-dm): Every time you die, you get resurrected after around 10-15 seconds. There is no shoptime, but you can buy spells by pressing ESC.
Deathmatch teams (-teams + -dm): Same as with normal deathmatch, but with prechosen teams.
Deathmatch shuffle (-sh + dm): Same as with normal deathmatch, but teams will randomly change every ca 5 minutes.
Ice (-ice): Enables ice terrain to randomly appear in terrain every round.
Square (-square): Changes the arena to be squared.
Circle (-circle): Changes the arena to be circle shaped. Is default.
Circle Donut (-circle donut): Changes the arena to be a round donut shape.
Square Donut (-square donut): Changes the arean to be a squared donut shape.
And then there are *a lot* of constants that you can manually change. For example, if you so wishes, you can change knockback to reverse by writing -c 3 -1. You can also change damage, knockback, life regen, arena shrinking, gold per round and the point system. You can also download the map maker and create your own arena.