Arundl has Mage Armor going during waking hours (included in the character sheets). Arundl’s “swiss army knife” spell is Evolution Surge, Lesser . It is super flexible. Specific evolutions that might be useful include Climb, Magic Attacks (if fighting something with DR/magic), Skilled (+8 to any one skill – especially useful with Use Magic Device), and Resistance (essentially energy resistance 10 for one type of energy). Arundl will also cast Haste on the party if it seems like a hard fight.
Arundl’s new spell for 6th level is Blade Tutor’s Spirit. It removes the penalty for using Power Attack for 1 min/level. Essentially a +2 to hit (since Arundl always uses Power Attack).
Arundl always prefers to use his eidolon, but is willing to go without it if we need subtlety (which we seem to rarely do). Without his eidolon, Arundl will use Summon Monster ability (standard action to cast Summon Monster III 9 times per day, lasts 1 minute per level). Here are some
As far as attacks, Arundl has 4 attacks per round. A bite attack (1d6+13+1d6 acid), a slam attack (2d6+9+1d6 acid) and two claw attacks (1d4+9+1d6 acid). The bite is the most damaging followed by slam followed by claw. So, if he has a single attack or opportunity attack, he will use bite.
Hit Points (with eidolon):
Arundl gets 35 temporary hit points from his eidolon. When he takes damage, they go first. If damage would take those hit points to zero (and kill his eidolon), he can prevent any number of those hit points by taking the damage himself. He usually leaves the eidolon with 1 hit point if this arises. The eidolon can’t be healed by anyone other than Arundl. The only spell that can heal the temporary hit points is Lesser Rejuvenate Eidolon. He can cast it and he has a wand of it. It gives 1d10+caster level (max 5) temporary hit points back.
Finally, at level 6, Arundl took the Flight (wings) evolution, so his eidolon has a pair of physical wings that allows him to fly at a speed of 30.
Level 5 Character Sheet (PDF)
Arundl (Level 5) with eidolon