I was already intending on having a strong mix of answers to permanent-based hate, but Oko is an extremely strong suggestion that I wasn't even thinking about for whatever reason. I definitely think Oko merits sideboard space.

I'm almost wondering if Dead of Winter would be viable in here as not only a way to kill multiple hatebears, but to just buy me tons of time against aggro decks in general.

I agree that artifact answers are valuable when possible since they help enable metalcraft.

Force of Will doesn't protect Echo once I've discarded my hand, but it does deal with problems like Karn from hitting the board and it's extremely versatile, so it's still something I am considering too.

I wasn't saying that my list is going to fizzle a lot, I was just pointing out one of the reasons that other Storm decks may not be building around Echo. It's servicable to hit the opponent with a mini Tendrils, because Echo can shuffle it back into the deck. An early Narset into Echo gives me plenty of time to reassemble. I don't expect to fizzle very often, but I do still need more playtesting.

I quite like the idea of boarding into aggro/control elements like Leovold, Oko, Riddlesmith, etc, but I'm not sure how much space I'll have to dedicate to that yet.

If I find myself fizzling too much, I'll look into running more draw, tutor, and/or engine cards.