New monster: Spirit Wolves

These are a stronger wolf monster for Forest, with a few quirks.

Ocassionally non-summoned wolves can howl for their pack, which
causes summoned spirit wolves to appear continously at intervals
from outside the player's LoS and track towards them, until the
effect ends. They have a very small chance of using this each turn,
rising considerably while at low health, encouraging players to
kill them quickly lest they be forced to deal with the rest of
their pack.

Additionally, the wolves' partially spiritual nature gives them
immunity to poison and negative energy, though they otherwise
count as living creatures.

As usual, I suspect the duration/frequency/number of summons will
need further adjustment once it has been seen in real games. It is
a bit tricky to preserve the feeling of a pack slowly converging
upon you without making the duration long enough to be obnoxious
or making the moment-to-moment density high enough to be overwhelming.

1 files changed, 2 insertions, 0 deletions

diff --git a/crawl-ref/source/mon-abil.h b/crawl-ref/source/mon-abil.h
index 25a0b5aa3b..2e75798a1b 100644
--- a/crawl-ref/source/mon-abil.h
+++ b/crawl-ref/source/mon-abil.h
@@ -40,4 +40,6 @@ void end_flayed_effect(monster* ghost);
 bool lost_soul_revive(monster* mons);
 bool lost_soul_spectralize(monster* mons);
 
+int spawn_spirit_pack(const actor* target);
+
 #endif