Arena Arc!

[Penelomeeg]

My players are entering an amateur arena competition after they finish their next job, they'll be level 2 and reach level 3 by the end of the arena. I have the teams they'll fight against (16 teams total in the whole competition, they'll have to be 4 other teams to win) built, but would like some advice on enviornments and obstacles added to the last 3 fights. The idea is each round the ring gets more complex. So by the final fight the teams are fighting the ring as much as each other.

Also any suggestions on small resolvable side quests or ibterests to spice things up and a suitable prize? I already have the winner of the entire thing gets a ceremonial dagger proving they were the winners of the contest (which gives them some rep around possible employers and respect with other guilds) all the gold from the entry fee each team payed (total of 76 gp) plus all teams get 5gp per win. What would be a good 2nd place prize and does 1st place already seem like it's good enough or should I add a magical item in there somewhere?

[ExLibrisMortis]

This is for D&D 3.5? 5e?

The cash rewards are low for 3.5 (don't know about 5e). For four on-level encounters, a second-level party would expect around 2400 gp total treasure split between four characters (and ~1/3rd level each), or half that for 1st-level encounters.

As for obstacles:
1) Moats, water-filled or no.
2) Walls, of course. Full height and half-height.
3) Anything you would find in a playground. Maybe a seesaw.
4) Fire pits, oil-soaked bales of straw.
5) Wild animals large and small.
6) Low-level battlefield control spells: web, entangle.
7) High ground, including multi-level towers.
8) Spike pits, caltrops, marbles.
9) Obstacles that appear and disappear from one round to the next.
10) Non-Euclidian arenas.
11) Fog and darkness (audience appreciation permitting).
12) Seriously gross smells, loud bangs, bright lights.
13) Spectators throwing tomatoes or rocks.
14) Timed challenges.
15) Fighter handicaps and odd weapon requirements.
16) Additional rewards placed in arena.
17) Particularly mismatched teams.

[Samzat]

Halfway into the round, the arena floods and rafts are deployed, so now you have to fight on 2 rafts

[noob]

Halfway into the round, the arena floods and rats are deployed, so now you have to fight on 2 rats
Seems an awesome idea!

[Honest Tiefling]

If you are ever stuck, make the arena completely advantagous for another team. For instance, a lot of beasts being sent in against a team of druids/rangers/hippies, or fire for a team of fire mages.

Turns out, someone has been bribing officials. So now the team has to find out who, how, and possibly even why and decide if they want to expose it or exploit it. This thread also works if the PCs lose, so you don't have to throw all of your hard work into the bin. You could also have an official of the arena really not want a certain group to win due to political, religious or racial reasons, and offer a huge bribe to sabotage them if the party doesn't get to keep being in the fights.

Other ideas include:

Forms of cover, if you play with a map
Gouts of flame
Random animals/elementals being thrown into the arena as well
Oily ground, making footing hard and fire spells either very successful, or very stupid.
Quicksand or gravel, making terrain difficult.
If the arena really doesn't care, throw in some hidden caltrops.