There is a large triangle point to large entrance and small arrowhead pointing right with continuation just behind triangle.

Go right

3 will get him home.

Left through the cobwebs they are fake to throw off any wary travelers, many traps are set and false arrows pointing to them be wise oberon

Lord Oberon should look to the right and notice the sparkling reflections above the right passage.  He will also notice the 3 marks carved to the right side of that opening.  If he follows that path he will find that for which he seeks.

Il y a une lueur en dessous de son bras, je pense qu'il doit aller en face.

i would chose the right route

According to the direction the triangle is pointing, right.

It is time to announce the result of our competition!

2,000 Sapphires are going to FAILO!

Congratulations!