[Unknown Mod][Combat] Experience points are given for all creatures that have been decimated during combat

[LeHerosInconnu]

Experience points are given for all creatures that have been decimated whether they've been present since the start of combat, or were generated during combat, and whether temporarily or permanently.
This applies to summoned elementals, ghosts, and other creatures that may be generated temporarily or permanently during combat.
Of course, decimated and resurrected or reanimated creatures (with the resurrection, the resurrection true or the animate dead spells) are only counted once for experience points, and regardless of whether they were present at the start of combat or were created during combat.

This is not an option.
This can be implemented directly in fheroes2.