Where can I find the antlers?

[CreamKaKao]

I'm Act 4 and I have not seen traders sell antlers or falling off the ground. I want to make knockdown arrows

[wendigo211]

One of the vendors in the market sells archer supplies. If you're lucky you she'll have some knockdown arrows, but it's all up to the RNG. If you rescued the fletcher in the sawmill in Reaper's Coast he also sells special arrows, so that doubles your chances.

Getting antlers is a lot more difficult, just keep checking the merchants and maybe you'll get lucky.

[Nixatan]

There is a pack of deer on backside of paladins bridgehead - Got 4 antlers off those - One was Adult antler - for whatever (haha) - Not far from Driftwood.