Just a comment about the Sacrifice spell. I recognize the need for Sacrifice 3 when playing as a warrior. I had the same experience as you. It is barely enough to create a new level 5 unit. Now, as a mage, things are very different. I haven't even bothered to learn Sacrifice 3. Sacrifice 2 is often too strong. With Int=58 and 2/3 through the game Sacrifice 1 does 1460 and Sacrifice 2 does 2925 points of damage. I often have to use the Archmage's Magic Shield to reduce the effect by 50%. Even Sacrifice 1 with the Magic Shield is sometimes too strong... But I guess that is "luxury problem"
(a norwegian expression meaning that it is a problem because you situation is too good - not sure about the english expression for this)