How do I beat Camelot?

Just lvl heracles up to LV80 and it should be easy with a merlin, maybe also swap Xuanzang with emiya (after you lvl him up too), try to keep heracles alive as long as you can.

Level up your servants, you've lots of amazing unit and slow down for a bit.

Material farm place :
Eternal Gear is in America, Chicago and London and Camelot Atlas Institute. It's also come as a prize for clearing Prison tower event. Recommended to farm it from event only, the free quest drop rates sucks !
Heart of foreign god, Prison tower event reward. No available free quest to farm for HOFG yet, recommended to farm from event.
Octuplet Crystal, Prison tower event reward and node with golems ( Camelot holy city, Septem and etc ). Farm only from event, unless you need few materials then go farm for it.
Dragon reverse scale, Babylonia - Nippur. Farm from event is more recommended.
Proof of Hero, Oceanos first free quest node with lots of pirates and Prison tower reward. The best place yet to farm this material.
Void dust, prison tower event reward and Camelot gold rush and etc. Farm only from event, like mentioned before the drop rates suck !
Ember Cards, Ember gathering daily quest. Available for every days LOL !

Make sure you don't skip Prison Tower Challenge quest, this event can give you almost all the materials that you truly need. If this event is too hard for you, then you can wait for Valentine events.

with those line up and u still ask how to beat camelot ?? shame on you !

I will be honest, I cheesed the whole fight with Mordred by doubling up on Robin hoods.

I had the following team:

1. Level 60 Fuuma Kotarou with Battle of Camlann CE
2. Level 70 Support Robin Hood NP 5 with Kaleidoscope CE
3. Level 50 Tristan with MLB Holy Night Supper CE
4. level 60 Mash with Ideal Holy King CE
5. Level 60 Robin Hood NP 2 with Heavens Feel CE
6. Level 70 Eurayle NP 2 with Witch under the Moonlight CE

Chaldea Mystic Code

If I recall right I had Fuuma hit Mordred with His Sabotage so that Robins Poison wouldn't be resisted. Then I let him get hit by Mordreds NP which charged up Support Robins and Tristan's NP gauge. I then used mash to get their defenses up and fired off their NPs. From there I used my CDs to keep robin alive.

When Mash and Tristan went down My other Robin and Euryale came out. I used the healing and Evade of my Mystic code to keep Robin 2 alive long enough to fill his and euryale's NP and have them finish mordred off.

It went pretty quickly IIRC.

Ascend David for the AOE evade, he has a good NP ST.

I kicked Mordred Ass with Robin, David, Waver and Mash. Robin evade was very useful (you need ST Quest to unlock it).

Maybe you failed because you tried to just manhandle her, go for a stall: stun, evade, invulnerability, NP drain...

I'll offer the way I beat Camelot: Hans (sometimes with Mash, particularly with AoE-spamming enemies) + support DPS. I think this is way better in general than using a support Waver/Merlin when things get tough, and your own DPS is not yet fully leveled.