This is an optimal build for Rene.

Take out ghostblade (brutalizer is fine, but ghostblade is bad. You get 15% cdr from your boots already. The armorpen alone isnt worth so much gold and the active doesnt suit his playstyle)

gj phil collins. great udyr guide btw

I won't vote yet, mainly because you've got lots of changes to make.

- Why is your build so lacking? Take out Wit's End and replace it with Maw of Malmortius and replace Thornmail with Randuin's Omen. You don't scale with ATKSPD, so why buy Wit's End? Randuin's Omen also gives you much better stats overall than Thornmail.

- Take Greater Seal of Armor instead of your current seals. You lack armor early game without these.

- Consider taking Ignite instead of Exhaust to burst people down faster.

- You need to learn how to code. For example, Renekton, Slice and Dice, etc. Refer to this guide for details.

Let me know if you're done improving it and I'll check it out.