Durations

[Sandman25]

What are typical durations of abilities? It is hard to make decisions when duration is unknown. For example, I have just met Actaeon and the only new ability it has is Quelling Cry (Debuff, Cooldown 6, 70% chance to decrease offense by 20%). If it lasts 15 turns, then it is really great. But if it's just 6 turns, then it is not a big deal. Similar problem with special Echeneis who had +25% defense in 2 abilities, for example. I ignored it but it could be a mistake if the abilities last 15 turns.
I know I can carefully analyze battle log but it is not exactly easy as there is no DCSS' Ctrl+p functionality, only messages from last turn are visible.

[Ferret]

Most durations fall into standard groups:

Non-SPD related stat Buff/Debuff (OFF down, OFF up, etc): 25 turns
Standard (most): 10 or 15 turns
Crowd Control (Paralyze, Sleep, Charm, Panic): Randomized, usually low (2-8 turns)
Elemental (Ignite, Chill): 3 turns
Turn Loss (Shock, Stun): 1 turn

If the word "briefly" is included an ability description, the effect will last less than normal for that type of effect. (ex: Healing Factor gives "brief" Regeneration, lasting only a few turns instead of the usual 10.)

So, stat debuffs like what Quelling Cry does usually last 25 turns. However, Quelling says "briefly", and it is true: Quelling's debuff only lasts 10 turns. Still, this is pretty solid.

Apologies that this isn't better spelled out in game yet.

[Sandman25]

Thanks a lot! I underestimated buffs/debuffs...