Spread the light, my child.
Henzell says...
  1. When you 1) move away from monsters, and 2) they move towards you, and 3) they didn't perform an {attack of opportunity}, then the amount of time taken to do its turn has an equal chance of being 0.1 turns slower, 0.1 turns quicker or being the normal amount. Over time, these 0.1s add up or cancel out to cause 'double moves' or 'lost moves'.
  2. This feature, in conjunction with {attacks of opportunity}, makes pillar dancing less viable and the threat of same-speed monsters less binary with respect to distance. A kobold with an electric dagger 2 tiles away is better than 1 tile away, but due to random energy you aren't completely safe walking away!
  3. When a monster gains/loses a move is when it is most likely to lose/gain it again. The worst case for a 1.0 move delay monster and player is a double move every 10 turns. Waiting while a normal-speed enemy approaches will assure that the enemy won't get an extra attack due to random energy or {attacks of opportunity}.

Information based on master branch and the great LearnDB.
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