iserith
Magic Wordsmith
When I use Morale (typically only in games where killing monsters does not confer XP), I write it in as a trait on the monster's stat block. For example, "The monster tries to escape when it reaches half its hit points or fewer, if it can." There's no check. It just happens when the trigger is met.I tried to use it, and it is very different. The huge randomness of the d20 makes it far too swingy, as opposed to the 2d6 or 2d10 from BECMI and 2E. Additionally, the flat DC:10 doesn't take into consideration the typical courage of each creature, since simple predators are much less likely to stick around than mindless undead. Theoretically the DM could set the DC for each monster, but that goes back to my original issue.
Players start to pick up on this and actually adjust their tactics accordingly, I've found. As an example, last session the PCs were trying to beeline it back to town to confront some rivals without going through too many resources and before some helpful buffs wore off. Along the way, a random encounter was indicated - 14 relatively weak monsters with the aforementioned Morale trait. Knowing they flee at half hit points, rather than try to kill each of them, they'd just try to knock each one to half hit points and and allow it to flee. This made it easier for them to conserve resources for the battle ahead.