Pretty self explanatory, a wiser opponent may notice the debuff appear on their character if you're hiding in a bush nearby.
Your defining ability. With it maxed out it will fear your target for 3 seconds, which is amazing, and you can get it down to around 7 seconds cooldown with high cooldown reduction items.
In lane save this for the ADC when they have fully committed to the engagement.
If you think the jungler might be around, save it for the gank, if they show up one fear should end the attempt.
In teamfights you are primarily a PEELER, that means you will fear the enemy assassins/bruisers who are diving on your carries. Eg. Akali, Katarina(especially when she ults), Khazix, Zed, Jax etc. This ability is incredible at peeling and completely shuts them down.
This ability will keep your health topped up in lane. Try not to expose yourself when you're draining, and be kind to your ADC and cancel the drain before you finish off the cannon minion.
It's generally not worth using this when you're chasing, or even under attack unless it's a last ditch effort to survive whilst your AD carry is killing the aggressors.
E: Dark Wind
Possibly one of the best level 1 abilities in the game, it costs 50 mana so you can pretty much cast it whenever you want, but you can use this to deadly effect if you pick the right moment.
The ideal time use it is when the ADC and Support are standing near each other with no minions around, it will bounce 5 times between them(silencing each hit), and doing close to 300 damage to the pair of them. It's devastating in the early levels and will allow you to take total control of the lane.
Try and remember to cast this either before or after you have feared someone, that way you get the most out of the debuffs.
You won't want to level this ability past 1 until all the others are maxed as you just get a small damage increase for a vastly increased mana cost.
Another signature skill, brilliant for jumping over a wall on to unsuspecting opponents.
Has very high base damage so you will still be scary even without AP items, just be weary of getting interupted during the channel while you cast it.
If you can hit level 6 before the other side you can do a devastating crowstorm on them almost guaranteeing a kill of 1 or both of them if your ADC is ready and you have fear/exhaust up.
Another tactic in lane is to hide behind the wall by your first tower,(works fine with blue or purple side), and have your ADC bait them to engage on the tower, then you pop over and destroy them.