Question about Crafting
 

Noob question here:

Can you sell crafting diagrams and still make the items afterwards? - Is it retained knowledge once you have them? Or can you not make the items without the diagrams?

Thanks!

Iirc, you need to have the diagram in your inventory to be able to craft that item.

As JDR have said: you need diagram to craft an item.

Okay thanks. Too bad, each one of those things takes up inventory space. Not much, but still.

Ok, this is a different question, but I don't want to start an entire new thread for it: Do potion effects stack if you have him drink 2 of the same potions at the same time? Say 2 Swallows at once, is that = Swallow effects x2? I'm replaying, and would like to know about Mongoose, actually.. :P

IIRC, after choosing a potion to drink, all potions of that type temporarily vanish from the inventory to prevent stacking and drinking a same type of potion in two separate meditation sessions won´t work either, the effect(s) just get replaced.

I don't see how stacking the same potion would be a big advantage anyways, since the toxicity would also stack.

Nope as people said. You can naturally quaff a Gadwall and Swallow if you like although
White Raffard's decoction + Gadwall should be enough of a buff for about any fight (Just
make sure you invest on catalysis and potion Specialization if you really want them to
make a difference in this game imo).

Keep in mind that potions are mainly useful in the early and middle stages of the game, so there's no need to hoard them. By the end you'll be more than powerful enough to get by without them.

Depends really.

There is a certain fight (with a lofty vantage) in the end that I couldn't have pulled off without my Raffards+Gadwall+Virga Combo.

But maybe it was because I was playing on Hard and only had basic Quen.

No need to hoard them with the ingredients respawning anyway (much more if you max specialization) . I left flotsam with almost enough to last me the rest of the game and there is a huge supply in Vergen too if you go that path. Just be sure to pick everything you find.