time its active element is triggered. As water floods a
chamber, the characters must swim across areas they
could walk through just a round or two earlier.
Since a complex trap remains active over the course
of several rounds, it might be possible to predict its
future behavior by examining how it functions. This
information can give its targets a much better chance of
thwarting it. To minimize this possibility, design your
trap so that it presents multiple threats that can change
each round. The changes can include how a trap targets
creatures (different attacks or saving throws), the dam-
age or effects it produces, the areas it covers, and so
on. Some traps might have a random effect each round,
while others follow a carefully programmed sequence
of attacks.
Dynamic e lements usually occur according to a sched-
ule. For a room that floods, you can plan out how the
rising water level affects the area each round. The wate r
might be ankle deep at the end of the first round, knee
deep the next, and so on. Not only does the wate r bring a
risk of drowning, it a lso makes it harder to move across
the area. On the other hand, the rising water level might
allow characters to swim to the upper reaches of the
chamber that they couldn't get to from the floor.
Dynamic e lements can a lso come into play in reaction
to the characters' actions. Disarming one e lement of the
trap might make the others deadlier. Disabling a rune
that triggers a fire-breathing statue might cause the
statue to explode.
CHAPTER 2 ( DUNGEON MASTER'S TOOLSTRIGGERS
The advice on triggers given for simple traps also ap-
plies to complex traps, with one exception. Complex
traps have multiple triggers, or are designed such that
avoiding a trigger prevents intruders from reaching the
area the trap guards. Other complex traps use magical
triggers that activate on specific cues, such as when a
door opens or someone enters an area without wearing
the correct badge, amulet, or robe.
Look at your map and consider when you want the
trap to spring into action. It's best to have a complex trap
trigger after the characters have committed to exploring
a n area. A s imple trap m ight activate when the charac-
ters open a door. A complex trap that triggers so early
leaves the characters still outside the trapped room, in
a place where they could decide to close the door and
move on. A simple trap aims to keep intruders out. A
complex trap wants to lure them in, so that when it acti-
vates, the intruders must deal with the trap before they
can escape.
The trigger for a complex trap should be as foolproof
as you can make it. A complex trap represents a serious
expenditure of effort and magical power. No one builds
such a trap and makes it easy to avoid. Wisdom (Per-
ception) and Intelligence (Investigation) checks might
be unable to spot a trigger, especially a magical one, but
they can still give hints about the trap before it triggers.
Bloodstains, ashes, gouges in the floor, and other clues
of that sort can serve as evidence of the trap's presence.INITIATIVE
A complex trap acts repeatedly, but unlike characters
and monsters, traps don't roll for initiative. As mechan-
ical or magical devices, their active elements operate in
a periodic manner. When designing a complex trap, you
need to decide whe n and how often its active elements
produce their effects.
In a trap with multiple active elements that work in
concert, those different elements would act on different
initiative counts. For instance, on initiative count 20,
blades sweep across a treasure vault, driving the charac-
ters back into the hallway. On initiative count 10 , magic
darts fire from statues in the hallway while a portcullis
falls to confine the characters.
Initiative 10. If a trap's active element takes time to
build up its effects, then it acts on initiative count 10.
This option is good for a trap that functions alongside
a llied monsters or other guardians; the delay before it
acts can give guards the chance to move o ut of its area
or force characters into the area before the trap triggers.
Initiative 20. If an element is designed to surprise
intruders and hit them before they can react, then it acts
on initiative count 20. This option is generally best for a
complex trap. Think of it as the default. Such a trap acts
quickly enough to take advantage of most characters,
with nimble characters like rogues, rangers, and monks
having the best chance to move out of the area before
the e lement activates.
Initiative 20 and 10. Some active e lements are in-
credibly fast acting, laying waste to intruders in a few
moments unless countered. They act on initiative count
20 and 10.