1. Cast Light improves visibility a little bit, so it’s handy to have around.
2. The easiest strategy of fighting the horses is blocking. However, while easily done, you need particular gear to do it. The horses deal a lot of poise damage, so you need a high stability shield (65+), with high lightning and physical protection (physical should be 90%+ and lightning 80%+). A decent shield for doing this is the Mastodon Greatshield; you can infuse it, but this isn’t necessary here. Another option is using Strong Magic Shield on a 60+ stability shield. And of course there is Havel’s shield.
After a horse makes a melee attack, and you block it, there will be a short window when you can attack safely.
3. The horses don’t sit somewhere and wait like normal creatures. They just have a chance to spawn in certain “danger zones”. When you enter this zone, there is a chance the horse will spawn, and there is another chance after a couple of minutes, etc. This means that if a horse spawned somewhere, never stick around for any reason; buffing/healing at this location is more likely to just spawn another horse. Similarly, if you fight a horse too long, another will eventually show up, so high DPS is absolutely necessary.
4. The horses don’t spawn when you’re inside a building, and as far as I can tell you can stay there forever.

1. Have a human phantom(haven't tested by myself). 2. Use the ring that increases poise damage for more stuns. 3. Have both people use a broken santiers or similar twinblade. 4. Stunlock for the win. 5. Punish those stupid Reindeer.

this entire area is the horses way of getting payback on humankind for creating beastiality videos.when in doubt, just blame it on porn

Endearingly referred to as "Horse***** Valley".

Seriously, I just got ganked by 3 horses and some warrior. I wouldn't mind that much if it didn't take me half an hour of walking through a eyesoringly bright area to get there. I won't give up until I've beaten it, but I sincerely doubt I'll revisit it in a NG+; this is far from my definition of a challenge.

need help in frigid anyone?

easiest way I found is call all 3 npc phantoms, they are generally standard dungeon cleaning party, tank, caster/healer and bowman, bring warmth to heal them before boss fight

this is always worked for me in NG, all you have to do is survive and help them abit, and I always had this feeling that they would make it without me

I found that for strength/melee builds it was worth it to put just enough levels into attunement to get a single spell slot and then use the pyromancy 'warmth' to keep the health of the NPC phantoms topped-up as you make your way to the boss. After clearing out every building, I'd cast warmth to let the NPCs camp out and heal up. It isn't quick, but aside from the Pharros Lockstone healing pool it's the only way low faith characters can heal up the phantoms and make sure everyone has a full health pool going into the boss battle.

Right when I summon Vengarl, I run a bit up the side of that hill and go straight, I only have to kill like 5 horses that way. I actually defeated Lud and Zallen on like my fourth try. That was hard as heck, especially when Zallen starts healing himself.. If anyone needs help out there?