someone might cast charm person on a creature be-
lieved to be a humanoid, not knowing that the target is
in fact a vampire. If this issue comes up, handle it using
the following rule.
If you cast a spell on someone or something tha t can't
be affected by the spell, nothing happens to that target,
but if you used a spell s lot to cast the spell, the slot is
still expende d. If the spell normally has no effect on a
target that s ucceeds on a saving throw, the invalid target
appears to h ave s ucceeded on its saving throw, even
though it didn't attempt one (giving no hint tha t the c rea-
ture is in fact a n invalid target). Otherwise, you perceive
that the s pell did nothing to the target.Areas of Effect on a Grid Invalid Spell Targets 8S
The Dungeon Master's Guide includes t he following
s hort rule for us ing areas of e ffect on a grid.
Choose an inte rsection of squa res as the point of
origin of an area of e ffect, then follow the rules for that
kind of area as normal (see the "Areas of Effect" sectio n
in chapter 10 of the Player's Handbook). If an area of ef-
fect is circular and covers a t least ha lf a square, it affects
that s quare.
That rule works, but it can require a fair amount of
on-the-spot adjudication. This section offers two a lterna-
tives for determining the exact location o f an area: the
template method and the token method. Both of these
methods assume you're using a grid and miniatures of
some sort. Because these methods can y ie ld different
res ults for the number of squares in a given a rea, it's
not recommended that they be combine d at the table -
choose w hicheve r method you a nd your player s find eas-
ier o r more intuitive.TEMPLATE METHOD
The template method uses two-dimensional shapes
th a t represent differe nt are a s of effect. The aim of the
method is to accurately portray the le ngth and width
of each area on the grid and to leave little doubt about
w hic h creatures are affected by it. You'll need to make
these templates or find premad e ones.
Making a Template. Making a template is simple. Get
a piece of paper or card stock, and cut it in the shape of
the area of effect you're us ing. Every 5 feet of t he area
equa ls 1 inch of the templa te's size. For example, the
2 0 -foot-radius sphe r e of the fireball s p ell, which has a
40 -foot diame te r, would translate into a circ ula r te m-
plate with an 8-inch diameter.
Using a Template. To use an a rea-of-effect te mplate,
apply it to the grid. If t he terrain is flat, you can lay it o n
the surface; otherwise, hold the template a bove the sur-
face and take note of which squares it cover s or parti ally
covers. If any part of a square is under the template, tha t
square is included in the area of effect. If a creature's
m iniature is in a n affected square, that creature is in
the area. Being adjacent to the edge o f the template
isn 't enough for a square to be included in the area of
effect; the square must be entirely or partly covered by
the template.
You can a lso use this method w itho ut a grid. If you do
so, a creature is included in a n area of effect if a ny part
of the miniature's base is overlapped by the te mpla te.
CHAPTER 2 I DUNCEON M ASTER'S TOOLSOtl\GRl\M 2.1:
CONE TEMPLATESPHERE TEMPLATEDIAGRAM 2 .3 : SQ.Ul\RE
AREA USING TOKEN SDtAGRAM 2. 4 : 5Q.UARE
AREA WIT H TOTAL CovER