None of the Grandmasters are challenging as its just remembering spawn conditions and curating loadout to enemy types and resistances to w/e the most common elements are. Grandmaster NF's should take no longer than 15-25 minutes at most, the fact there is lots of just filler crap to pad out the strike time is obnoxious just look at the meatball in Lake of Shadows or the Ultra Tormentor in Hypernet where it feels like most of your time in the strike is spent just chipping away. Rewards are also not good enough for time invested as well, builds are too heavily limited due to power disadvantage amount and modifiers. Warlocks are just Stasis Turret spam or Wellbots + Starfire. Titans just spam Overshields or Suspends now and Hunters just sit in the corner and stealth because their other subclasses can't really get any use because of the bad design. Heist Battleground isn't hard its just tediously sleep inducing, its not a curated well thought out and designed strike its just a seasonal activity they shoved into there because "Uhh... why not, they're kinda like strikes aren't they?"