Cube Fragment Monsters can be found during Fortnitemares, Fiends, Elite Fiends, Brute, Elite Brute and Mega Brute (Yellow/Gold).
Elite Brute will spawn about halfway through the match while the mega Brute Monster only appears at the very end of the match. Starting when around 10 players are left.
Youtube Playlists (Season 6):
Season 6 Challenges
Fortnite WEEK 8 How to Complete Stage 3: USE A RIFT Challenge in Season 6
Fortnite WEEK 8 Fastest way to get Trick Points in Season 6 (Easy Trick Location)
Fortnite WEEK 8 Fish Trophy Locations (Season 6 Challenge / Dance with a Fish Trophy)
Season 6 Secret Battle Stars
Secret Banner Location WEEK 8 Fortnite | Season 6 Hunting Party (Secret Battle Stars/Banners)
Fortnite | All 7 Secret Battle Stars & Banners to Unlock Hunting Party Skin (Season 6)
Secret Battle Star Loaction WEEK 7 + Hunting Party Skin | Fortnite Season 6 A.I.M Outfit
Season 6 Map Changes
Flying Chair / Mini Cube appearing in Superhero Base in Fortnite (New Event Changes Season 6)
Complete Butterfly CUBE EVENT in Fortnite | In-Game View of New Map Changes after Massive Event
Chiller Trap Trick to Travel Faster in Fortnite (Fastest Sprint Using New Freeze Trap in Season 6)