123, The Battle for Gobwin Knob, Page 111

[Lamech]

Most caster types are glass cannons. They dish out lots of damage at range, but it also takes very little damage to croak them. It's usually cost effective to kill them as quickly as possible, to reduce the amount of damage you take.

If casters aren't damage dealers, they are healers. Healers are even worse, as they are force-multipliers. It's usually mandatory to kill them first, otherwise you can't kill anything. (I play a priest in WoW, and I can tell you, everyone kills the healer first.)

The most dangerous thing about casters in games like is not being able to heal, that can be horrible, but AoEs of any sort are even worse. Its why templar, defilers, and such are so insanly powerful in Starcraft. AoE's can make overwhelming numbers useless (or worse), if they can hit everything you have with one shot. AoE buffs/debuffs can one side have a huge advantage. If AoE healing is fast enough the whole army is very hard to kill.

Its possible Webinar thinks if the caster lives he can't win, or maybe the tunnel forces all lose if the dirtamancer lives.