When I started playing this game it ran flawlessly and didn't encounter my first freeze until several hours in. It eventually became a nuisance due to freezing every or every other battle requiring closing the application via End Task in the Task Manager.
I looked for tips/solutions but did not find anything specific and reports and recommended solutions are sparse as there's no exact reason why or when the game will freeze. I learned that sometimes just highlighting tiles would freeze the game, often casting a healing spell would freeze the game, or moving a player character too quickly.

Given that this game was released a decade ago, the recommended OS is now in the End of Life phase and the recommended GPUs are considered ancient by today's performance metrics, this leads to software/hardware issues that would not have been known when the game was released.

This guide hopes to make an unplayable game playable.

Set the properties to Run as Administrator and in Compatibility Mode

Browse to the install location (typically C:\Steam\steamapps\common\Blackguards)
Blackguards.exe Properties > Compatibility tab > check the box Run this program in compatibility mode for: Windows Vista SP 2

In the same tab, check Run Program as Administrator

Modern day GPUs are often bundled with 'smart' software that tweaks and often overrides game settings. Many times it works out of the box but sometimes it causes problems. This was the case for me freezing on the same battle over and over again no matter what. Adjusting these setting made it less likely to lock up and playable. It seems (from user posts) the Nvidia software is a bit more problematic.

I write this as an AMD user but adjustments for Nvidia software is more or less the same.

Open up the software your system uses, like AMD Software Adrenalin Edition or Nvidia GeForce Experience.

Find individual game setting (or global settings) profiles, and disable any fancy options that override individual application settings. For AMD software, for example you have the following: Radeon Super Resolution, Radeon Anti-Lag, Radeon Image Sharpening, Radeon Enhanced Sync, etc.

All other options such as Vertical Refresh, Anti Aliasing, Tessellation, should all be set to "Use Application sttings".

Remember, this is an old game, many of these fancy GPU tweaks were not available or were just coming out - you pretty much do not want the software overriding or adjusting any settings aside from the settings set in the game application.

Go into the game options in Steam and in the General tab add the following to the Launch Options:
-d3d9

This forces the game to run in DX9 and seems to be a fix for modern GPUs.

Some Nvidia users that had issues were able to fix their problems by adding the following to the Launch Options:
-force-gfx-direct

A lot of older games have trouble when modern day GPUs are able to run at 3x or more the FPS than what was possible when the game released.
This particular title runs around 300 FPS for me, quite the overkill some would say, and I agree. Locking the FPS pretty much solved most of my freezes making it possible to play and finish this title.

You can use any software to do this, I personally Use RivaTuner now but have used FRAPS in the past.