Ice shield reduces damage by 1, and blocks on average 9 of 19 attacks.
Anyway, the water and time decks were my most common opponent in my run, and they usually weren't that much trouble.
The reverse times are more annoying than the shield, really.
The entropy foe is always a bother. An early discord is difficult to overcome, though thankfully there's only one of them.
The devourers slow you down a bit, but they aren't too bad. Chaos seed can hurt a lot though.
At least the demons aren't an issue for frog-atrice rush, unlike for most other lvl3 farmers.