Sara Heritage is a freelance contributor for IGN.
Here are two decklists I've won tournaments with a Red-White Aggro Burn deck and an Azorius Control deck, each with vast differences in the number of cards I played in their sideboards: Boros Burn | Modern | Roman Fusco, SCG IQ/1st Creatures (12) 4 Eidolon of the Great Revel 4 Monastery Swiftspear 4 Goblin Guide Instants (16) 4 Lightning Bolt 4 Lightning Helix 4 Boros Charm 3 Searing Blaze 1 Shard Volley Sorceries (12) 4 Rift Bolt 4 Skewer the Critics 4 Lava Spike Lands (20) 3 Mountain 4 Sunbaked Canyon 4 Inspiring Vantage 3 Bloodstained Mire 2 Scalding Tarn 2 Sacred Foundry 2 Fiery Islet Sideboard (15) 4 Smash to Smithereens 4 Skullcrack 3 Kor Firewalker 2 Path to Exile 2 Searing Blood With the Burn deck being a dedicated strategy of every card trying to deal three or more damage to my opponents, my sideboard options were very limited

So long as you're playing with a bunch of cards with good enter-the-battlefield triggers, like Skyclave Apparition, Agent of Treachery, and Deadeye Navigator, you can rinse and repeat until you've taken over the game
The hexproof is also puzzling for anyone not playing a Noyan DarNoyan Dar deck
(When a creature with renown 1 deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.) Whenever a renowned creature you control deals combat damage to a player, double the number of +1/+1 counters on it
Pair it with some sacrifice synergies and all it truly costs you is a single mana