Nothing like playing against Relic War and playing Sanctify into Benediction.
They can't cope.
I like Sanctify a lot, because pretty much nobody has it in their deck, so whenever you play it the opponent must be like, "What the hell, man?"
It's always annoying having to deal with a fully warded board.
Zoo Light is pretty decent. I don't even play Irina or abuse Camaraderie much, yet I haven't dropped out of Mythic in like a month or so. Back when I played only Lusters, I would drop out every other week.
Oh, if you go second into an aggro deck, you know they will be holding a bunch of creatures, some of which will be out on board faster than you can kill them, owing to them going first.
So like, you give them an increased chance of drawing a buff, I feel, and buffing said creatures on the following turns while not really improving the situation down on board.
But yeah, it's kinda random since you don't know if the mulligan went well for the opponent. But if it didn't, even less reason to have them draw again.
If it went well, they must have some bodies out on board, and you risk having them buff it on the following turns more. If it didn't go well, then you help them fix their hand.
This is all assuming the aggro opponent is going first.
HRD into Zoo Light—I would be even more scared of using Ludia if I am going second, because Light wouldn't mulligan for Worship (unless they go second, they can keep it if it shows up), and if you make them redraw they can get Worship, and you also waste 1 mana. Just too risky in this particular matchup in my opinion. I could be wrong though, I don't have much experience playing HRD, just saying from my perspective of playing against it.