Then I got Pathfinder® Roleplaying Game: Pathfinder Unchained™. If you are a GM that makes your own monsters, GET THIS BOOK! I cannot stress enough how much this book really saved my game. By the time I finished making up monsters for playtest mountain, I was able to make up monsters in 20 minutes. The best part is that I don’t feel like these monsters are any less worthy at the game table than monsters made the traditional way. They were just as good and no one at the table knew which were made with which method.
So let me share with you some monsters that came out of those mad monster creation days.
Armored Veth’thar CR/HD 6
Init +0; Perception +11 (darkvision 60 ft., low-light vision, tremorsense 30 ft.)
Size Large; Speed 20 ft., burrow 20 ft.
Defenses
AC 23 (touch 5, flat-footed 20); Fort +9, Ref +9, Will +5; CMD 24; SR 17
hp 77
Attacks
Melee gore +16 (2d6+12), 2 tentacle sting +11 (1d6+4 plus intelligence suck)
Attack Options (DC 14) intelligence suck (1d2 Int damage, Will negates); CMB +16
Statistics
Str +6, Con +4, Wis +2; Climb +14, Perception +11, Sense Motive +11
XP 2,400; NE magical beast (earth)
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Jon Brazer Enterprises 
Seems a bit tough between the intelligence suck (damage?), high AC, huge HP, and high damage if all attacks hit with those high attack bonuses. Remember, it’s not supposed to actually THREATEN a 6th-level party of 5 characters, just require them to spend 20% of their daily resources to kill one off. This seems a bit too strong by that metric.
Actually, the HP is inline with a car 6 monster. While it does have a high ac, its touch ac is very low. So is its will save. And believe it or not, its damage is inline with other cr 6 monsters, even with the int damage. Agreed, its attacks are high, but it doesn’t sugar coat the damage like standard monster design says to. Normally, monsters at this level are getting area effect abilities and auras. This is a tank, plain and simple with some obvious weaknesses to exploit.