?
how dont you get the souls when you beat them?
and what is the minimum requierement to get to drangleic castle?
You just need to beat the bosses / light the primal bonfires, or alternatively, if you have 1 million soul memory, you can open
The Shrine of Winter
It doesn't matter if you eat / use the boss souls or not.
You need to get to Drangleic Castle on your third playthrough. Bonfire Ascetics sadly don't work on the ghost. I tried it on my second playthough and it did nothing (kindled all 4 bonfires in the castle and the one in Shaded Woods with). I did use a bonfire ascetic on the Mirror Knight and the 2 Dragonriders on my second playthrough and defeated both for the third time. This might explain why the ghost sold me the spells as soon as I entered the castle.
Also, you don't have to defeat the 4 Bosses to get through Shrine of Winter. On the 2nd and 3rd playthrough, the shrine opens when you have a certain amount of soul memory. I can't tell you what it is exactly, but I think only the soul memory you amass in the 2rd / 3rd playthough counts (could be wrong about that) and the amount needed to open the door gets smaller and smaller the more primal bonfires you kindle on those playthroughs.
It's not just on consecutive playthroughs. I could open it just from doing a lot of co-op in NG.