Varying up a monster is a great way of keeping your players on their toes. By giving them something they don’t expect, they are not sure what else is changed. It will give them a moment’s pause.
When you change a monster, pick a theme. Let that theme guide you in varying that monster. Take the will-o’-wisp as an example. Vary that up with a goblin theme so your first change should be to change the damage type to fire instead of electricity. Then the next part you should change is their description and their behavior to be more in line with a goblin. This will allow you to put your own stamp on your game.
(Based on a will-o’-wisp)
This faintly glowing ball of red and orange light bobs gently in the air, the nebulous image of a goblin’s skull is visible somewhere in its depths.
Goblin-O’-Wisp CR 6
CE Small aberration (fire)
Init +14; Senses darkvision 60 ft.; Perception +17
AC 27, touch 27, flat-footed 16 (+5 deflection, +10 Dex, +1 dodge, +1 size)
hp 40 (9d8)
Fort +3, Ref +13, Will +9
Defensive Abilities natural invisibility; Immune magic
Speed fly 50 ft. (perfect)
Melee incinerate +17 touch (2d8 fire/18-20)
Str 1, Dex 31, Con 10, Int 15, Wis 16, Cha 14
Base Atk +6; CMB +0; CMD 25 (cannot be tripped)
Feats Alertness, Blind-Fight, Dodge, Improved Initiative, Weapon Finesse
Skills Acrobatics +21, Bluff +11, Escape Artist +21, Fly +31, Perception +17, Stealth +25
Languages Aklo, Common
SQ feed on fear
Environment any swamp
Organization solitary, pair or string (3-4)
Feed on Fear (Su) Anytime a goblin-o’-wisp is within 15 feet of a dying creature or creature subject to a fear effect, it gains fast healing 5.
Immune to Magic (Ex) Goblin-o’-wisps are immune to all spells and spell-like abilities that allow spell resistance, except magic missile and maze.
Natural Invisibility (Ex) Goblin-o’-wisps have the ability to extinguish their natural glow as a move action, effectively becoming invisible, as per the spell.
Find ways to vary up more monsters with the Book of Beasts: Varied Monsters at JonBrazer.com.