Laning Furion?

I've played hundreds of matches pubbing as Prophet, and yes he can be played quite well as an off-lane, or any lane for that matter. Its a matter of preference, for Nature Prophet is extremely versatile in a sense and either jungling or laning is just whatever you feel comfortable with or necessary.

Hope that helped :D

P.S., maxing out sprout is unwise til late game for the most part, but the 5 sec disable at max is extremely deadly on any Hero who cant brake through trees. Timbersaw and Windrunner along with Treent are very obnoxious when it comes to Sprout and thus are much harder to take care of as such.

He works decent mid, and is a decent offlaner as well. Not that he is survivable, in fact he is probably one of the easiest to-deal-with offlaners, it's just that you basically use his treants like Lone Druid's bear to block the pull camp, or pull the creep wave making it difficult for the enemy to deny you experience/farm. If they have a strong trilane though, you're easy to kill even under tower, so be weary of that.

If you play natures prophet on easy lane so you can farm that'd be a nice ideea since you'll usually find more farm on lane than in the jungle, mid laner the same, if you don't have to deal with a nuker and you play wisely, and as an offlaner he's squishy and without a solid escape mechanism he is a sure target for most of the trilanes out there.

If you've got the micro skills, he's a great hero on either the offlane solo or safe trilane carry.
I actually ran him not long ago with a jungling ls, me as NP and a support in lane babysitting NP.
I was able to last hit (well, sort of) as well as stack and pull the camp using treeants.

running him offlane is a bit different but he can farm very quickly with a few levels. Once again, using your mad micro skills (lol at mine) you can block camps and pull the creep wave to your tower. Also, you should be fully ready at level 3 to gank like crazy. If mid or safe lane pushes up, tp in and sprout. I know sprout is awful at low level but it slows them down enough for a hard stun.
Natures prohpet is the king of kill stealing. If played well, he is a massive PITA because of what he can do, even from low level.
You see their mid bottle crowing? Tele to their fountain, kill the courier then buy a tp from their fountain and get back in lane.
They're playing 5 man dota? tele to the far away lane, spawn treeants, get them to push and get back for the team fights.
They're split pushing? Tele in and stop the push or shoots their creeps from across the map (ulti)
They're trying to farm that spectre/am etc, tele in for the gank.

Natures Prophet is either really good, or completely useless dependant entirely on the person playing him. He is one of those heroes that fits most line ups and can do pretty much any role. I've even played him as a hard support with Mek, force staff and arcane boots (along with Bas ring for armour aura) with reasonable success (not his best role but meh)