This creature looks like a dark storm cloud, with sparks suggesting eyes and long sweeping arms charged with bolts of lightning.
Medium Lightning Elemental
CR 3
XP 800
N Medium outsider (air, elemental, extraplanar)
Init +8; Senses darkvision 60 ft.; Perception +7
AC 16, touch 15, flat-footed 11 (+4 Dex, +1 dodge, +1 natural)
hp 26 (4d10+4)
Fort +5, Ref +8, Will +1
Immune electricity, elemental traits
Speed fly 100 ft. (perfect)
Melee slam +8 (1d6+3 plus 1d4 electricity)
Special Attacks metal mastery, spark leap
Str 14, Dex 19, Con 12, Int 4, Wis 11, Cha 11
Base Atk +4; CMB +6; CMD 21
Feats Dodge, Improved Initiative, Weapon FinesseB
Skills Acrobatics +11, Escape Artist +9, Fly +12, Knowledge (planes) +2, Perception +7
Language Auran
A lightning elemental gains a +3 bonus on attack rolls if its opponent is wearing metal armor, is wielding a metal weapon, or is made of metal (such as an iron golem).
A lightning elemental gains a +10 bonus on bull rush, disarm, overrun, and trip attacks when it charges a creature against whom its metal mastery ability applies.
Pathfinder Roleplaying Game Bestiary 2, © 2010, Paizo Publishing, LLC; Authors Wolfgang Baur, Jason Bulmahn, Adam Daigle, Graeme Davis, Crystal Frasier, Joshua J. Frost, Tim Hitchcock, Brandon Hodge, James Jacobs, Steve Kenson, Hal MacLean, Martin Mason, Rob McCreary, Erik Mona, Jason Nelson, Patrick Renie, Sean K Reynolds, F. Wesley Schneider, Owen K.C. Stephens, James L. Sutter, Russ Taylor, and Greg A. Vaughan, based on material by Jonathan Tweet, Monte Cook, and Skip Williams.