Comparing boots+tear to a catalyst, assuming we take catalyst early game, seems nice as you get more mana from tear over time plus the mobility, however the things that catalyst offers you over tear are A) HP, this helps for survivability, and B) Sustain, this is the important one, every time you level up you regain HP and mana for leveling up, now this bonus is huge while in the lane, its like having a mini Soraka in lane with you.

As far as farming, I don't last hit with spells without blue buff, I save my mana for harassment, she doesn't have a mana return on her spells like Karthus, Annie, or Malzahar, so if you last hit with Cassiopeia's spells, you will assuredly run out of mana unless you rush AA all the way to get the bonus mana regen. Her auto attack animation isn't the best in the game, but its plenty sufficient for last hitting creeps.

As far as AA's AP gains, believe me, I'm not arguing that it is a bad item as far as flat AP goes, as it has the potential to give you a lot of AP. What it lacks is anything else. Just to list a few items, Deathcap, it gives 140 AP +30% AP from all other items. This means it self synergizes for flat AP plus makes AP on all other items better, thats why its basically required in all nuker's builds. Rod of Ages, it offers AP, HP, and Sustain in lane from the HP and Mana regen from leveling passive. Rylai's Crystal Scepter offers AP, HP, and a 30% (In Cassiopeia's case, 15%) slow. Abyssal Scepter offers AP, MR, and MPen for your entire team. Will of the Ancients offers AP and full team spell vamp. Then you look at Archangel's staff, its an expensive item that offers mana, which most team comps will not run 2 mana dependent heavy nukers, most will run a single AP nuker, and another AP tank/tanky DPS type, so you should be running blue buff after your jungler uses it the first or second time it spawns, and it offers AP, and while it has the potential to offer a LOT of AP, it also takes time before that AP comes to show. If a game carries on to 45+ minutes, then your investment in AA is a great choice, as you will have that maxed, your RoA maxed, you will probably have a Banshee's, etc, but it offers no early game survivability, not much early game damage, all it offers is early game mana, which does not give your team any early game advantage, and as the mid AP, you need to take advantage of early-mid game as that is when AP shines the greatest, and you can lead your team into having the late game advantage.

As far as the seals go, thats .4 regen per seal, which means x9 that is 3.6, on top of the 3 regen from support masteries, thats already up to 6.6, and thats only by level 6.

I am not sure AA staff doesn't have any utility. First of all, the staffs prequisite the tear of goddess, is an easy to get item (with only 600 gold, where you get the maki pendant at start-up for 390), and you keep the mana bonuses when you upgrade it to the staff. So actually you can start increasing your mana at the very start of the game, and you can get an additional boots of speed, instead of spending the gold for the catalyst.

Second, none of the Cassiopeia's spells except twin fangs is a direct kill spell. I mean with that if you want to kill minions and get the gold, you cannot rely on the poison effect because it is not easy to predict whether the poison will kill the minion or to time the finishing attack (which is also not an instant attack). So to ensure you get the gold you have to finish with a twin fang, which costs good mana for early levels (especially if you think you are going to max it first) and both maki pendant and the tear have mana regeneration which can keep you in lane, spamming skills and without skills you can never get any kill.

Third, the AP boost of archangel staff is not bad at all. Not to mention that you get an extra 1 ap, for each 8 skill you have made, even if you are not using the staff at full performance, you can easily get bonus 500-600 mana, since you can spam noxious blast while you are walking idle per 3 seconds, and stacking it together with the bonus base mana the staff provides and with your champions actual mana, you can easily get around 2000 mana which gives you +60 ap, increasing the bonus AP of the staff to +105 ap and making it the second most ap increasing item in the item selection.

Not to mention, I don't have any premade team, so it's not a sure thing that I am the only one AP spammer in the team.

Also mana regeneration seals per level give 0.065 /lvl, so at lvl 6 or so you will have only around .4 reg / 5 seconds, with 9 seals 3.6 reg / 5 seconds, which is a **** adjustment anyway, so I would prefer bonus base health seals or bonus health reg / lvl seals.

I find that AA is cost inefficient, as it provides no survivability or utility, it gives you mana which is great and all, but by the time you have capped out the mana given by Archangel's Staff, you should be the person on your team receiving all of the blue buffs, as you are primary AP damage for the team. Which means all the item gives you in real value is AP. If you build a RoA, a Banshee's Veil, and another item with mana on it, and you cap out the mana gain on the item,the item could be worth more than the cost in the long run, but most games you will not be able to completely fill out your build, so its better to buy items that give both a great boost early for an early advantage, like RoA, Deathcap, or Rylai's, and hold value through out the game. Archangel's staff in my eyes takes too long to make itself worth the cost, however if a game were to drag out, then it would have been a good investment.

For Cassiopeia's early game, whenever your jungler will need blue, I advise mana regeneration per level seals to provide her some great mana sustain.

In my opinion tear of the goddess and later archangel's staff is a must for Cassiopeia. Without any mana regeneration and mana boost, you are not able to spam many skills, even though you have a %50 mana cost reduction. As far as I have seen, Cassiopeia is not a nuker but is similar to a AD champion using magic attack instead of physical attack (because of twin fangs). Using archangel staff, this skill spamming benefits you with more mana and more AP.

Just went 5-0 with this guide. thanks a lot! Free cass week ftw

+1.

Great guide, went 10/3/6 first game with this build. Crazy sustain damage, +1.