Hey this is my first Build but i think udyr is good with this because i play him so too and so nocturne or xin 2 hit's death :)

I use and pick Ignite and Ghost because:

Ghost:
With the Bear skill you run fast with ghost faster, so you can hunt runner and stun them and kill them.

Ignite:
It's useful in a team fight and in the early game!
Because:
When you push down an enemy under 200 or something and he run you ignite him and he is death
in a teamfighter:
When you attack with you team you can damage 2 enemys in the same time so you can kill one guy and can after him kill the next! :)

Don't say what because Runes..
Sry i don't know about runes for udyr i have pick the best one for him because i have other one now because not enough IP :D

When i have mor runes and test's game with them and udyr i Update this :)

Wriggle latern is cheap so you can buy it early.

Then when you need more place for you Items you Sell wirggles because then you must have a fully bloodthurster and und you buy the second or infinity edge.

And you can so good farm creep's because wriggles passiv!

Sorry when my guide is not the best and my english too :o

because:
I'm German and it is my first guide/build ever :)

Have fun "!