Poison cloud may be useful at the beginning of a battle with many enemy stacks. If your initiative is greater, they won't be able to move out of the cloud. I remember it being somewhat useful in KB:TL.
Timelessness might be good when you have a lot of buffs on a unit (especially buffs like divine armor and hell's breath with short duration). You only need to cast timelessness every 4 rounds (or more with creation and possibly high intellect, if it's affected by that) to keep the buffs. At least I hope it works that way
