This is a series of bugs of the original Heroes 3

Messy stack quantity calculation and battle result
When you cast a spell that creates a new stack, for example, Summon Water Elemental or Clone, the game will:
- Check if the current stack quantity is <20 by checking the value in Combat Manager->54BC (Example: 0x59EFE8 when summoning elemental)
- look for the first available stack id and use it for this new stack.

If a stack has the flag Summoned and Killed (This happens when a clone is killed), the stack id will be marked as available, and when you summon another stack in the battle, this stack id will be occupied by the new summoned stack. Here we have some inconsistency:
1. Despite a Summoned/killed stack id can be used for a new summoned stack, yet when checking the current stack number, the game uses Combat Manager->54BC. This value isn't updated when a summoned stack is killed, thus, it is possible that there is still vacancy left in the battlefield, yet the game tells you "already 20 stacks and you can't summon any more units".
Here I provide 2 videos:
Video 1 - current stack quantity not updated when summoned unit killed
The stack id number in Combat Manager->54BC, after a summoned stack is killed, still shows the current stack quantity as 18 (should be 17), and when a new stack was summoned, the killed summoned unit's stack id was occupied and the current stack quantity was also 18.
Video 2 - once reaches 20, no longer possible to summon even if the summoned unit killed
Once we reach 20 units on the battlefield, it would not be possible to summon more units even if a summoned unit is killed.

Testing script in the video:

2. Since the game recycles Summoned/killed stack slots, some data would be overridden when a new stack is summoned and uses a stack id that previously belonged to a summoned creature. This creates a new issue that we no longer have the data of the previously killed summoned stack, which is reflected in the battle result screen.
Video 3 - the killed summon unit is not shown in the battle result once another unit uses its stack id
As you see from the video, the casualty is none (the killed Earth Elemental stack isn't shown). But if I didn't summon a new Earth Elemental stack, the killed Earth Elemental would be shown there.

My thought:
1. The stack quantity at Combat Manager->54BC should be updated immediately after a summoned stack is killed. This avoids the fake message claiming the battlefield is full after reaching 20 stacks for once.
I could probably finish this task on my own.
2. When a stack is summoned and uses a stack id that is previously occupied by a summoned stack, the previous stack info should be saved somewhere and use when showing battle results.
Haven't tried but I probably need some help with this task.