It's a great tool for protecting creatures from certain types of removal, especially when you can toss one around at instant speed
Its a flat-out generic tutor for 5 mana, and a lot of its value comes from the fact that it can be reanimated for additional value later on
The cards exiled with Ob Nixilis, Captive Kingpin are able to be used until your next end step
As I said in my last article on Premodern, I really like old frame cards and I collect them
Eldrazi typal strategies love this, as does anything that uses a lot of morph or disguise effects, as those are colorless creatures on the stack, too
For its part, Ivy Lane Denizen puts a +1/+1 counter on any friendly creature that enters the battlefield