Teach sirens a new offensive trick

A long-acknowledged problem with sirens is that while their
mesmerisation can be powerful and relevant when supported by dangerous
allies, they are completely harmless on their own yet can still camp
out where you can't reach them and prevent you from leaving as well.
The solution I propose to these staring matches is to make lone sirens
actually dangerous and so I am giving them a powerful and thematic form
of offense: calling up the spirits of the drowned to inflict the same
fate on their captive audience.

When a siren starts to sing, it starts a counter that will (after a
short time) start to continuously call up drowned souls from nearby
deep water. These drowned souls have very short duration and die upon
hitting something, but their touch inflicts considerable AC-ignoring
drowning damage.

Since mesmerisation can already be powerful in the presence of allies,
said counter will not be incremented in the presence of more than a few
HD worth of them (and thus sirens with existing support will not call
up drowned souls). This ability is intended foremost to give threat to
the many sirens one encounters WITHOUT any backup to speak of without
making all others much more dangerous.

I think requiring deep water to perform this ability could work well with
their already-existing behavior to pull the player towards this terrain
and gives a powerful incentive to try and not let that happen.

Most of the numbers involved here are provisional, including rate of
soul calling, damage of individual souls, number of allies required to
inhibit using it, etc. The idea is that it should be quite dangerous on
its own without making situations where a siren's presence is already
dangerous far moreso, but nor should one or two harmless monsters prevent
it outright.

Let's see how it plays.

1 files changed, 1 insertions, 1 deletions

diff --git a/crawl-ref/source/mon-behv.cc b/crawl-ref/source/mon-behv.cc
index f90d25d3b6..cc994bb182 100644
--- a/crawl-ref/source/mon-behv.cc
+++ b/crawl-ref/source/mon-behv.cc
@@ -800,7 +800,7 @@ void handle_behaviour(monster* mon)
                     else
                         _set_firing_pos(mon, you.pos());
                 }
-                else if (mon->type == MONS_SIREN && you.beheld_by(mon))
+                else if (mon->type == MONS_SIREN)
                     find_siren_water_target(mon);
                 else if (!mon->firing_pos.zero()
                     && mon->see_cell_no_trans(mon->target))