Here we will see a few parameters to pay attention to such as:
Wave current order
Spawn time between 2 heroes in a hero spawn.
A group of monsters from slot i. Slot hero i (i = 1 -> 5). After producing all 5 slots in order i, a new wave will be formed.
Time interval between 2 hero slots in hero production.
The hero's base HP multiplier after each wave.
Monster kill amount increases with each wave.
The hero's base HP multiplier after each round.
The figure below will better describe the stats mentioned above in the first wave of the battle.
First wave of battle