Wave master Support

In the first round if you don't have the wave master upgrade (AOE hit 12 dmg) or the villager just let the wave master die and see what the enemy minis are.
Now here it gets good.
Use your healer/villager and support the wave master. Snipe the back not defended minis by using the spear goblin or if your back minis have a mini in front, use your bowler with the first ability (Clash! deals 16 dmg). Now if you don't have the AOE upgrade on your wave master you CANT WIN so use your cycles to get the wave master.
If they have monk or skeleton king or the pink hair hero, you have to defend the bowler WITH YOUR LIFE and get his third upgrade (his normal nit gets pierce). The bowler is you win condition in that moment. In frenzy time, you should've already make a path for your bowler to hit the hero. He gets a infinite value if he is close or even 3 tiles away from the enemy hero. Now. If you still get countered, use your skelly guard and his 1st and 3rd ability (1st gives 6 more shield, 3rd if his shield gets broken an nearby ally gets it) (you can use only one if you don't have the elixir even tho you should have it). Your skelly is just used to bait attacks and let the wave master to its thing with the hit speed.

"I don't want to read this🤦‍♂️"
-Okay so here is in a short way.

1st round.
-Wave maste if no upgrades pop up
Or
-Use villager/wave master 2nd upgrade if it pops up

2nd round.
-Use bowler or/and spear goblin to snipe minis with weak hp.
-Upgrade the wave master and villager (if you have the elixir)

3rd round.
-Put the healer on the map.
-Upgrade her with the 2nd and 3rd (or 1st instead the 3rd)
(2nd upgarde, her healing spear has a bigger range, 3rd ability, healing spear gives "unstoppable" [unstoppable: doesn't get affected by any stun or any bad ability] 1st ability, healing spear gives 10%+ more hp"

If you lost.
4th round.
-Use your bowler with the 3rd ability and put the skelly guard in the play to defend the bowler. (3rd ability, attack gains pierce)
-upgrade the minis on the map that can win the match (mostly healer or villager)
-Move your wave master away

If you still lost.
5th round.
-Upgrade everything u can and even move the wave master away if thats the issue (if u didn't already do it)

That's all!
Good luck in the arena :)