The plan for the staff of herding drops from Izual in Act 4. I'm pretty sure it will drop on any difficulty, but as a rule of thumb it's a good idea to run the highest difficulty level you can run efficiently/quickly.
5% drop rate (Blizz has said at times they increase or decrease this drop rate but we don't really know): so count on having to kill him 20 times to get the plan to drop, but hopefully won't take that many runs... although RNG (calculated in part with a Random Number Generator) means it could take more than 20.
If you are hunting cosmetics then look for a cosmetics community where many folks have already made the staff and party up with them. Rock onward.
Edit: Get the parts in Adventure mode. Those guides are great but a little outdated.
After I got the Gibbering Gemstone in this season with my first Chiltara kill (lucky, I know), I decided to hunt down the other parts, and strangely, it took quite some time to get the plans from Izual, but they dropped eventually.
Difficulty doesn't matter. I ran normal for quick clears while searching for parts.
If you don't want to mess with the parts and just want the Rainbow Sword transmog, let me know & I'll use my Staff of Herding (Non-Season-North America-Soft Core) to open the Whimsyshire portal until you get the Rainbow Sword drop: havik2k#1425
Icy Veins has a farily detailed guide on the whole process:
Does it still only drop off Normal Izul? or What?
RNG is RNG
its a 5% drop rate. along with the pieces
The plan for the staff of herding drops from Izual in Act 4. I'm pretty sure it will drop on any difficulty, but as a rule of thumb it's a good idea to run the highest difficulty level you can run efficiently/quickly.
5% drop rate (Blizz has said at times they increase or decrease this drop rate but we don't really know): so count on having to kill him 20 times to get the plan to drop, but hopefully won't take that many runs... although RNG (calculated in part with a Random Number Generator) means it could take more than 20.
If you are hunting cosmetics then look for a cosmetics community where many folks have already made the staff and party up with them. Rock onward.
Edit: Get the parts in Adventure mode. Those guides are great but a little outdated.
"Son, you got a panty on your head..."
After I got the Gibbering Gemstone in this season with my first Chiltara kill (lucky, I know), I decided to hunt down the other parts, and strangely, it took quite some time to get the plans from Izual, but they dropped eventually.
So, the plan still drops, yes.
My D3 armory
My Youtube Channel
+difficulty = better chance of drop.
Items from HS can drop from any level and difficulty mode.
Gibbering stone is the hardest to find.
Difficulty doesn't matter. I ran normal for quick clears while searching for parts.
If you don't want to mess with the parts and just want the Rainbow Sword transmog, let me know & I'll use my Staff of Herding (Non-Season-North America-Soft Core) to open the Whimsyshire portal until you get the Rainbow Sword drop: havik2k#1425
Icy Veins has a farily detailed guide on the whole process:
http://www.icy-veins.com/d3/staff-of-herding-whimsyshire-guide
Let me know if I can help. Good luck.