Alchemy - Worth 18 Runes?

[deepblue9k]

So I've been playing on my mage and just reached level 9 with quite a few runes saved up. I have more than enough to upgrade Alchemy from level 1 to level 3 but I'm wondering: is it worth it?

I'm just not sure how hard crystals are to find. I know in KB:TL, I invested in alchemy and was happy with it since I probably would have run out of crystals without it. But Treasure Searcher seems to provide me with a good number more crystals than in KB:TL (it's two free chests EVERY battle). I don't want to invest in Alchemy only to find I have way more crystals than I need to upgrade all the spells I want.

So can anyone who has finished the game tell me if Alchemy is useful or just a waste of runes.