Which spells do folks consider worth learning or upgrading ?

[Sandsai]

You're missing the point. The point is that direct damage scales very poorly in general. The point was that late game it is far more beneficial to go with buffs or debuffs that work on a percentage basis. Pain mirror is very useful in this regard, so is pigmy, so is bless and all other percentage based spells. Initiative problems are solved by onslaught for a warrior. A fast moving troop and phantom image or just teleport allows for any melee troop to reach the other side in one turn, boom shooter problem solved.

To demonstrate the lack of a proper scale lets take your own example. 300 damage vs. -20% in health and damage of a 1-2 tier stack. Recalling from memory, swordsmen have 35 hp, tier 2. Thats 3500 hp you take -20% hp that is more than double of the 300 damage spell. You also reduced the damage by same amount. This is a level one pigmy spell. So as you can see, direct damage scales poorly in relation to percentage based spells.