The Son of Mimir stays silent, and stares at you with serious concern. After a moment of pondering, he grabs you and lifts you on his shoulders, before he climbs one of the trees surrounding you.
"Now Mortal, let me be frank with you, you are no fallen warrior, because you are not dead. I have no idea how you got down here into hel or how you made it out of it and into the iron forest without being devoured by fenrirs spawn. But let me tell you with whatever luck or skill you managed that you won't climb Yggdrassil."
With those words you break through the eternal gloom of the dark forest below and finally get a view of the surrounding lands. As you look around you see that the iron forest stretches on for endless miles into both directions and you realize quite uncomfortably that no matter for how long you walked you couldn't have possibly gotten this deep into the forest on your own two feet.
"Mortal, look over there" he points into the dark gloom of the night ahead of you. You look but you can see nothing, it is too dark, something seems odd about the darkness though.
"Look closer." You look closer but still you cannot make out anything.
[7-15],[82+16] then you finally realize what he is getting at. with a dawning feeling of horror you realize that it isn't dark, that it is not night, that what you percieved as eternal darkness is in fact Yggdrassil, you are staring at a part of the World Tree a very, very, very small part of it.
Numbed you look up and see a single leaf in the far distance and you have the sobering realization that the leaf is at least several dozen square miles across and that that is the only reason you can see it from such a distance.
"Yggdrassils trunk is at least 5 months of foot travel away, and we are talking about the walking speed of a jotun. Not that of a mortal man. The Tree itself is thousands of miles across, no one has ever rounded it completely. No one that i know of. Mortal, you have to get there and climb through all the eight worlds, you have to fight Ice Giants, The Giants of Muspellheim, you have to deal with treacherous dvergr and the wiles of the Ljolsalfar, you have to walk the ends of Midgard, your home and even then, you have to find the Rainbow Bridge and then you haven't even fought one of the gods yet.
Mortal what you propose is folly. You won't achieve anything on your oath, not on foot, not by mortal means."