Rammus actually is a terrible jungler, his ganks are really good but that's about it. He sucks at doing objectives, sucks at farming, sucks at soloing the enemy jungler, sucks at invading, he sucks at every jungler thing he does. Junglers also get reduced levels and since rammus scales very good with levels rammus jungle is very sad with no levels.

Rammus top lane fixes all the problems. He has one of the best wave clears if done correctly, incredible scaling into late game, one shots adcs, very slippery to catch and good at splitpushing.

To know how to wield this weapon you must first know what counters rammus the most.
when against rammus you must build as much attack speed as possible so that you can kill rammus when his W is down.
Blade of the ruined king is particularly very effective against rammus because it does max health damage AND it reduces rammus's movespeeds after 3 attacks, which automatically procs after he taunts u.
Berserker greaves and guinsoo's is very good against rammus too because you want to have the most attack speed for the least amount of gold spent. Look for gold efficient items that also give attack speed and you are set to defeat the armordillo.
If you're an ap champion, try building more damage against rammus instead of health. You need a heavy duty tank killer to shred through his armor, so things like rod of ages and riftmaker that gives health is bad. The best ap item against rammus is NASHOR'S TOOTH. This goes back to the attack speed argument where you must kill him quickly when his W is down and since nashor's tooth gives a magic damage on hit in addition to the attack speed, it is VERY effective at killing rammus. Liandry's is probably the second best item against rammus. Even though it gives health, it also does max health MAGIC damage, which kills rammus very quickly because he doesn't like to build MR.

Since rammus is a scaling champion, he has one of the WORST early games in all of league of legends. Before thornmail,you should never EVER be able to kill any champion. To add on to that, rammus' short range means he is easily poked out by any champion under his own turret. Even if you are chovy at last hitting you will still be poked out after 1-2 waves and either have to recall or be open to a dive. Rammus is also terrible at clearing the wave without having the minions hit you. In order to get through the early game without giving up plates and top prio, you must proxy as much as possible.

First thing you do in every single game should be to go into the enemy top side to look for a proxy level 1. To do this, follow the optimal pathing guide.