As someone who plays Karlov of the Ghost Council, I am speaking about myself here
Include a high energy count, as well as energy recycling ( Superior Energy Retrieval and Mela) and acceleration (cards in this list), for sustained attacks
Check out the Modern Horizons 3 Card Image Gallery to see cards from these decks and the rest of the set
Especially ones that can play Odd-Eyes Pendulum Dragon
Magic Online Society's website and Discord are good places to start down the player-run-events path, and Cardhoarder maintains a list of them as well, although I'm not sure all of the events listed are still active
The philosophy we set up in that hackathon was that a Modern Horizons set wasn't about making new mechanics but harnessing all the mechanics from the past, making use of the heightened complexity to create designs that we couldn't normally make, including mixing and matching old mechanics and doing tweaks on old cards and themes