Death Magic on the Battlefield

[MaxWilson]

Niarg said:
When I tried shadow blast 3 D4 mages set to cast it 3 times killed about 20 enemies.
They targeted areas with few troops in and often missed completely, also they seemed to concentrate on a single mass of enemies and attempt to kill every last one rather than targeting for the most damage.

Any ideas on why it was so ineffective for me?

Poor precision? And, possibly, not a big enough army on your side. You want to combine Precision 14+ with some troops of your own to hit the sparse areas that have just had most troops killed, and to get them to clump up again for another Shadow Blast.

In general, arty AoE spells are not as good in practice as they seem on paper because even with good Precision, the AoE is somewhat randomly-distributed around the target point.[1] You can often improve AoE spells by giving the targets a resaon to stay clumped together (carrying a Bag of Winds is good, because the Air Elemental will attack on round 1 and they'll spend round 2 clumping together to destroy it). Alternately, use a BIG AoE and resign yourself to killing fewer units than you would think with pure spells.

-Max

[1] This makes the battle AI make poor choices because it picks spells by simulating the results a few times in its head, then picking the best result. I know it does this to choose spells and I think it might do this to pick spell targets as well. (Probably targets the center of each squad and sees which one does the most damage.) The randomness of spell AoE makes this a high-variance method in sparse troop formations, which means the naive "do what worked best in simulation" give poor results. BTW, "real" AoE spells like Thunderstrike and Banefire do not tend to suffer from this problem because they always affect a 3x3 square area.