At best, I could see Harold as a sideboard card to punish control decks that tap out for a sweeper or threat, but the original dream of one-shot people out of nowhere was getting further and further away even as the list improved
She is at worst a two in one card and at best a massive dangerous threat that you have to be most careful about how you deal with her
Traveling Chocobo is a fun addition that lets you play lands off the top of your library and can double up some triggers from the wide variety of lands the deck plays
If they draw, say, an Advocate of their own, the Rallier is just going to be a speedbump on its way to smashing your face in
Mairsil, the Pretender Instead of relying on a normal creature plan, Mairsil, the Pretender builds your deck around abilities
The strategy of a Trostani deck is pretty straightforward: ramp up quickly, create lots of creature tokens while playing big creatures, and lean into lifegain synergies