I've overseen hundreds of EDH league games, played in hundreds of EDH games myself, and have run infect in a variety of decks
The last ability triggers only once whenever you're dealt combat damage, no matter how many creatures deal combat damage to you at the same time
From Elesh Norn, Grand Cenobites master scheming and manipulation to Vorinclex, Monstrous Raiders primal strength, these cards really cover the bases when it comes to otherworldly dangers
Together with Hibernation Sliver the deck could have good answers to all anti-creature effects other than permanent barricades and have enough copies to make sure that each Sliver wave contained at least one
In fact, it will even exile itself if it gets destroyed
Most people know she is good but find it hard to fit her into decks over other things or don't appreciate the ways in which she is crippling for your opponent