Invisible Stalker

Species Traits
Invisible stalkers have the following traits.
Elemental (Air): Invisible stalkers have the traits and immunities common to elementals.
Natural Invisibility (Su): An invisible stalker remains invisible even when attacking. Creatures that correctly discern the stalker's location despite being unable to see it have a 50% miss chance on melee and ranged attacks.
Improved Tracking (Ex): Invisible stalkers are consummate trackers and make Spot checks instead of Survival checks to track a creature's passage.
Automatic Language: Invisible stalkers speak (but neither read nor write) Auran. They understand (but do not speak, read, or write) two other languages.
Invisible Stalker: CR 7; Large elemental (air); HD 8d8+16; hp 52; Mas -; Init +8; Spd 30 ft., fly 30 ft. (perfect); Defense 17, touch 13, flat-footed 13 (-1 size, +4 Dex, +4 natural); BAB +6; Grap +14; Atk +10 melee (1d8+6, slam); Full Atk +10/_+5 melee (1d8+6, slam), or +9 ranged; FS 10 ft. by 10 ft.; Reach 10 ft.; SQ elemental, natural invisibility, improved tracking, darkvision 60 ft.; AL none or master; SV Fort +4, Ref +10, Will +4; AP 0; Rep +0; Str 18, Dex 19, Con 14, Int 14, Wis 15, Cha 11.
Skills: Listen +11, Move Silently +15, Search +11, Spot +13.
Feats: Combat Reflexes, Improved Initiative, Weapon Focus (slam).
Advancement: 9-16 HD (Huge); 17-24 HD (Gargantuan).
Advanced Invisible Stalker: CR 11; Huge elemental (air); HD 12d8+48; hp 102; Mas -; Init +7; Spd 30 ft., fly 30 ft. (perfect); Defense 18, touch 11, flat-footed 15 (-2 size, +3 Dex, +7 natural); BAB +9; Grap +21; Atk +15 melee (2d6+12, slam); Full Atk +15/+10 melee (2d6+12, slam), or +10 ranged; FS 15 ft. by 15 ft.; Reach 10 ft.; SQ elemental, natural invisibility, improved tracking, darkvision 60 ft.; AL none or master; SV Fort +8, Ref +11, Will +6; AP 0; Rep +0; Str 26, Dex 17, Con 18, Int 14, Wis 15, Cha 11.
Skills: Listen +13, Move Silently +17, Search +13, Spot +15.
Feats: Combat Reflexes, Dodge, Improved Initiative, Weap-on Focus (slam).