Before we get started, I just wanted to say that this is my first guide. It will be a work in progress, so bear with me. My Name is ScorchReticle and I am a Gold Nautilus main (ew gold, such a low player, I know). I have over 130k mastery on Nautilus, so I think what I have to say might be of some use, even to player higher than me in elo.

The main objective of the early game is to keep your adc safe. There are 2 ways you can do this:

PASSIVE: If your adc wants a passive lane and wants to play the farming game, apply pressure by going to the sides. Anyone that knows Naut knows that if he lands a hook, it's deadly. When you have a stack up, use it to execute a minion, then keep applying pressure. Remember, the main goal here is to keep the adc safe, so use your abilities as you need them in order to achieve that.

AGGRESSIVE: Your adc wants to go balls to the wall and get kills early. Your goal is to land hooks on the enemy adc and harass them enough to where your adc pulls ahead in farm, if not even pull some kills. Use the sides of the lanes to get a good vantage point for your hooks. If there isn't an opening for a hook, use your E to help push the wave faster (but dont take farm from your adc unless you have a stack up). You want to be fighting as much as you can, but be smart about it. No need to take unnecessary risks.

First turret has fallen and it's officially mid game. The objective here is to secure objectives. The easiest way to do this (especially in low elo) is to look for picks and pressure objectives. Follow either the adc or the mid laner and do your best to pull them a couple kills. When your team has an advantage, push a turret/get dragon.

IF YOURE BEHIND: The most important thing you can do as support naut when playing from behind is to not get risky. This seems obvious, but a lot of people think "Oh, i need to get some kills or else its gg". If youre behind, the worst thing you can do is keep throwing yourself at the enemy team. Farm it out and win it in a late game team fight. Remember, as Nautilus, you have an unreal amount of CC. Use it to your advantage!

Nautilus is a peeling god. You have a pull, a root, a slow, a knock up, and a stun. In the late game, your objective is to peel for your adc. Do not let anybody touch them no matter what. As the support, its better that you die than your adc. Play smart, peel for your adc, and win the fight. You're a tank, keep that in mind.