So quick question
If you draw Corrosion:
Revelation - Discard Item assets from play and/or from your hand with a total printed resource cost of at least X, where X is the shroud value of your location. If no cards are discarded by this effect, Corrosion gains surge.
And all you have are zero cost item cards in your hand, are you required to discard them?
Hey Jobu,
Yes, you are: you discard as many cards from your hand / in play until you satisfy Corrosion's conditions. That means if you are at a shroud 2 location, you could discard just a flashlight and Corrosion would be satisfied. If you didn't have the flashlight and instead had a Rabbit's Foot, 2 Keepsakes and 2 level 1 magnifying glasses, you'd discard them all - because you need to keep trying to satisfying the condition.
It's covered on the arkhamdb FAQ for the card, too, btw, in case you want to see the ruling in Matt's own words! https://arkhamdb.com/find?q=corrosion 
+1. Corrosion is a nasty, NASTY card.
That's an interesting ruling. I never would have interpreted the card that way. If it said "Discard...until the total cost of discarded cards is X", I could see it.
It also seems inconsistent that you can keep a 0 cost card if you discard non-zero cost cards. If the idea is that you discard as much as you can, then those zero cost ones ought to go, too.
Edit: never mind on that second point. I misread it.
Edited by CSerpent2 hours ago, CSerpent said:That's an interesting ruling. I never would have interpreted the card that way. If it said "Discard...until the total cost of discarded cards is X", I could see it.
This is the key:
When a non-targeting effect attempts to interact with a number of entities (such as “draw 3 cards” or “search the top 5 cards of your deck”) that exceeds the number of entities that currently exist in the specified game area, the effect interacts with as many entities as possible.
In this case, if the X exceeds the total cost of available assets, it interacts with (i.e. discards) as many as it can, so all of them.
So basically, you lose all your zero cost assets, unless you have enough non-zeroes to pay the total cost. If X is 6 and you have a 2, a 3, and some 0s, you lose them all.
30 minutes ago, CSerpent said:So basically, you lose all your zero cost assets, unless you have enough non-zeroes to pay the total cost. If X is 6 and you have a 2, a 3, and some 0s, you lose them all.
Items, but yes.