Video Preview: Changing Monster Hit Points During Combat

I just did this last night. After the first round of battle I realized my homebrew creatures had too many hit points, and the battle was going to take too long, and not necessarily be interesting. The battle was not meant to be the climax of the session, and was more intended to teach the player about the nature of the creatures they would be encountering from here out. I feel like if a battle is going to exceed 3-4 rounds, it should be really important to the story and/or have a really fun mechanic, otherwise it can turn into a slog.

I think this all boils down to the intention of putting a monster there. If it was to show how easy it was to defeat it, and it lasts more than one round and manages to survive a spell, it went down, because that was the intent for the monster. If he has to say some things and battle starts, he'll probably parry and avoid while talking and either escape or fall as intended. and if the big bad is going down too fast, you either tweak it or add more supporting characters for the big boss that have some reason for coming late.