Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
why follow this guide
First off here's the reason why you should follow this guide.
I main Cassi
I've been using her since she came out. that means I bought her the day she came out. I had plenty of time to practice with her and use her. I do agree that she could use some buff to some point but used properly she can be devestating. For those interested i'll share my ideas of what kind of buff she could be given if riot ever looks up my guide and buff her throught one of their patch.
First thing you have to remember is that cassi is a mage and that she is fairly weak physicly and has low hp, Idealy you want to lane with a partner, someone that can more or less frontline and be the distraction of you. Your job is to harass and support with heavy firepower even stun or slow with your ultimate.
Very important if you want to use Cassi well, learn how to fast cast.
Use shift and the designated spell letter for fast cast of spell like twin fangs and the likes. But be careful, while fast casting, this also roots you in place until you stop pressing shift. Users be aware this is a dangerous... Big damage but also leaves you open for attacks. Also, try to keep in movement except when fast casting make yourself almost untargetable. You dont want to get stun... this could cause your death since your squishy
First skill you want to get is noxious blast, this will be your main harassing spell, althought weak early on, its ap ratio make it worth waiting abit to level up later. this will be the second spell you master.
How to use and applications:
harass and Scout the bushes with it. Very important, since you can spot with it enemies that are hidding in it thanks to the icon of the speed boost, also try to initiate a fight with it, its speed bonus aswell as poison will help you position yourself properly and combo with your killer spell, twin fangs, also do note it plays with your enemie's regen abilities and is a pain for healers and support. Keep in mind its your main harrass spell annd fight initiating mechanic. Dont be afraid to use it for hits and run because of its speed boost and turn your back to cast it to help you run away.
Second skill you get is twin fangs, this is your killer spell, make sure your enemy is poison when using it, you need its refresh to be active to use it to its full potential, thats why you always try to start your fight with noxious blast
How to use it and applications:
Simple enought, poison your enemy first then fast cast, its goal is simple, its your main kill spell, fast cast and kill.
Third spell is miasma, Helps you slow down the enemy and somewhat farming since the poison refreshes aslong as the enemy stands in it. Its not quite powerful, but I find its always good to have your 3 main spell when you start, this should be the last spell you master. more useful for farming then anything else, but thats just my opinion, but you can also use it to slow your opponent while running away.
How to use it and applications:
this is mostly to me a farming skill, but when in combat with other players, I suggest casting it right after noxious blast if possible RIGHT BEHIND THE ENEMY, the cloud grows slightly and should end up poisonning them and it will slow them if they try to run. again while poison use twin fangs.
Final spell, petrefying gaze, invest in it as soon and everytime you can simply put it etheir stuns or slows the enemy it will hit and damage them at the same time for a decent ammount.
How to use it and applications:
In short, you want to use thie etheir to initiate the fight, or right after your noxious blast to stun them and keep them from running away or simply slow them, but you can also use it to help you run away, but be careful the stun and or slow only last for 2 seconds its short, useful but short.
Sadly you need clarity, if you want to lane longer, you need it to stay on the lane longer and level faster Cassi will eat throught her mana very very rapidly during combat against another player even with her passive ability. the other ability I suggest using is ghost walk, helps you escape from your enemy aswell as chase them down, and combined with noxious blast speed boost, it almost takes care of your lact of speed.
Items are pretty much staples for a spellcaster, you Mainly want to focus on ap items. I suggest starting off with an amplifying tome and health potion, if played properly uou might not even use the potion early on, but its always good to have incase, next item is boots, get the speed 1 boots, you can compensate your speed with noxious blast, then move on after to blasting wand or soulstealer depending of the situation, I personnaly prefer to focus on the crystal scepter before because the slowing effect is a godly and almost necessary for cassi... and the health bonus is also very useful, after that completle your boots if you are facing any tanks or people with magic resistance, then build up to your rabadon s deathcap, finish off with void staff and will of the ancient, magic penetration and spell vamps will help you kill and survive.
You usually want to lane with someone who can draw attention from you while you position yourself or help run away, be careful thought you do poison and may end up doing several killsteal since your poison damage is damage over time. ideally, try to partner with a melee character, a fighter or tank, I beleive singe might be the best partner in some case since his poison works with your twin fangs
When it comes to Team fights, I know I am repeating myself, but you are a mage and support... you are squishy, stay behind your allies and support with firepower, another option is also to sneak around the team fight and attack from behind. you want to approach the enemy team from behind and cast your ultimate, stun or slow down enemy and even catch offguard the ones that are trying to run away. also since your noxious blast gives you a speed boost and ghostwalk helps your speed, you can chase easily your enemies but be careful not to be too greedy, dont forget your squishy and can fall into a trap.
ideas for possible buff eventually
* increase the speed bonus duration of noxious blast from 3 to 4 seconds
* increase the area of effect of miasma
* increase the duration of the stun/slow of petrifying gaze, as it stands it feels too short and with mercury threads... its almost unoticable
* finally increase her health abit... she is abit too squishy