We recently fought a Troll Vinespeaker in our DnD 4e campaign. These was some controvery over whether we could reduce the troll to less than 0 hit points to keep it from getting up the next turn, via Troll Healing:
If the troll vinespeaker is reduced to 0 hit points by an attack that does not deal acid or fire damage, it falls prone and remains at 0 hit points until the start of its next turn, when it regains 10 hit points. If an attack deals acid or fire damage to the vinespeaker while it is at 0 hit points, it is destroyed.
We mainly wanted to do this to tie up the troll until our Warlock could come over and destroy it with fire.
So, as per the rules, could we reduce the troll to negative hitpoints, or does it stop at 0?