One of my posts just got dogpiled by American (going by timezone difference) homophobic racists making death threats. That was a good opportunity to test Mastodon's block facility, which seems to work pretty well. It clears one's timeline very neatly and immediately.
I didn't bother reporting - their admins won't care. One positive response to the hate was from a user on one of their own servers - that user should consider moving elsewhere for their own sanity and safety.