Adjust antimagic mp drain against players (especially AF_ANTIMAGIC)

The amount of mp lost to antimagic attacks was highly erratic, being
based both on the melee damage inflicted as well as a large random
range. This was additionally somewhat problematic from a design
perspective as it was difficult to make an antimagic monster that
inflicted reasonable damage without completely draining your mana pool
in a hit or two.

AF_ANTIMAGIC now drains mp based on the attacker's HD instead of damage
done (provided the attack does pass AC, like many other AFs), and the
mp drain is more normalized, so the extreme highs and lows will happen
less often. The idea is that some mp loss will happen more regularly,
but this loss will be somewhat less spiky. Lom's melee might have gotten
a buff, but probably he can handle that.

I didn't adjust how antimagic WEAPONS work, as those involve more questions
of symmetry with the player, where damage inflicted might indeed be the
better baseline for the severity of the antimagic applied, but possibly
their mp drain versus players could be adjusted similarly, too.

1 files changed, 1 insertions, 1 deletions

diff --git a/crawl-ref/source/melee_attack.h b/crawl-ref/source/melee_attack.h
index d2ca0f3054..0ee2fb7ea6 100644
--- a/crawl-ref/source/melee_attack.h
+++ b/crawl-ref/source/melee_attack.h
@@ -125,7 +125,7 @@ private:
     /* Brand / Attack Effects */
     // Returns true if the defender is banished.
     bool distortion_affects_defender();
-    void antimagic_affects_defender(bool amplify_effect);
+    void antimagic_affects_defender(int pow);
     void pain_affects_defender();
     void chaos_affects_defender();
     void chaos_affects_attacker();