Explorer rings - which is the best for me?

Before Big bang, critical ring. After Big bang the rings looses the critical damage property, so you will have to choose between 2 att 10% (critical ring) crit rate or 3 att 5% crit rate (cruel ring). I'd say it's a no-brainer to get the the critical ring since 1 att is a mediocre difference in the wake of potential system.

Depends on what class too, y'know. Cruel ring would be best for classes without critical enhancing skills like SE or Critical combo. 20% damage is not nothing.

But anyway, OP, I'd say Cruel ring. Shadowers don't really have alot of criticals, and even after BB gives innate critical, the cruel ring will still enhance damage more than the critical ring.