Spectating a friends game when

I know the numbers... heck on the large thread on the cassi rework i was the guy constantly putting out numbers about how high her damage is.

DFG lasts 4 seconds You can land 8 fangs, but lets say you land 7 you can auto in between each fang but lets say you don't ( you can also points in between) and i am not going to use any ap ratios just base damage (besides it would help cass's case) i am also excluding poison damage This is also excluding 10% ap bonus from cass passive

Cass lands 7 fangs plus ult = 1235 damage.

This number while true is in a best case scenario. Normally you will not get as many spells as this off. Heck pulling out 7 twin fangs in 4 seconds even on a stationary target is hard since the game does not queue commands. What i mean by this is that even if you mash a button as fast you can there is going to be a delay between the spell going of cool down and you pressing 'e'. Beside this you have to remember that all her spells have cast time so when you cast her q or w you lose potential twin fangs and her twin fangs cast time combined with her slow attack animation means that if done perfectly she will not have time to aa (which on a side note does not get amplified by dfg since dfg only amplifies magic damage). Further you also want to kite as you are most likely not going to be left alone in teamfights.

Ahri lands full combo and hits everything 100% = 742 (with 20% extra damage on charm) Cass combo listed above plus DFG: 1482 Ahri combo listed above plus DFG: 742

DFG isn't about burst damage it's about how much dps you can put out in those 4 seconds. The numbers stated for both of my examples are both very possible outcomes in a skirmish. Another point i was to say is that cass does have sustain because of her passive. Liandrys is a great buy on her as well because it has synergy with her kit as well as doing a good amount of damage no matter how much ap you have.

I would like to say i disagree with you here. A lot. This would make dfg a good buy on ryze too who can pump out way more damage over 4 seconds than even veigar. A lot of this is due to the fact that you need to be targeting the same enemy for 4 seconds which is not guaranteed for sustained damage but is guaranteed for burst damage while they are cc'ed by ahri's charm. Another reason to get dfg on ahri and not cass is because ahri needs every bit of extra damage she can get for her burst since she wants to kill her target in that window while cass is going to kill her target and the rest of the enemy team if she gets time. The last big reason is build path. Ahri has plenty room for dfg in her build as she does not really need any items beside dcap and void staff (yes zhonya's is good but not necessary) while cassi needs extra mana from either roa or seraph, the slow from rylais, pen from void, dcap for extra ap and preferably a last item for extra defense so she can keep on staying in the teamfight even if she gets dove by an assassin or bruiser. A last minor thing i want to mention is that the 10% cdr you get from dfg is practically wasted on cassi but this is only a minor point.

On the liandrys then it is a bad choice on cass since she has very short ranged poke which is also not too easy to hit in the case of her q (which does not slow without rylais) and in case of her w then if you miss it or opponents manage to dive you before you have it back up then you are relying on hitting your q on whoever dove you and if you miss it you have a melee bruiser or assassin on top of you with 3 seconds before you have any kind of damage. In an all in it should be clear enough that liandrys is not good. The dot it gives is simply too small compared to the damage cassi puts out through her e.