Good item for my Animal Companion's neck slot?

[claudekennilol]

I've got a worg that I ride around on. I've also got Pack Flanking which he also has.

One thing I was considering was a Menacing Amulet of Mighty Fists. I was also considering Fortuitous because me and my pet are built around massing AoOs. Any other thoughts about what else I could throw in my worg's neck slot?

[GoldEdition42]

There is a Dire collar which will Enlarge Person (Animal) on him for 1,000 gp.

Also one that costs alot more, the Dire Collar Greater. Animal Growth is what it does but it costs 14,000 gp.

[Markov Spiked Chain]

Spell Storing is a good option too, but Menacing with Pack Flanking is hard to pass up (if you're not using Reach.) I like Frigid Touch for Spell Storing, as it shuts down a full attack response. But Spell Storing Armor also works fine for this.

[claudekennilol]

Dire Collar won't work on a worg, it's a magical beast, not an animal.