Here is the full list of all 50 Ultra Savage achievements.
Defeat Nahash
Do Ten Time Travels
Enhanced Item +10
Have Over 300% ATK SPD
Do Six Time Travels
Deal Over 1'000'000 Damage
Enhanced Item +6
Defeat King Bera the Reaper
Reach Level 100
Defeat Lord Pretty Face Coolinagi
Do Your Second Time Travel
Reach Level 80
Have Over 100,000 HP
Have Over 50% CRIT
Deal Over 100'000 Damage
Defeat Raki-Raki The Demolisher
Have Over 100 CHI
Do Your First Time Travel
Defeat Liki Lee The Amgi-Turner
Deal Over 9'000 Damage
Reach Level 60
Defeat Heli Boss
Maxed Out A Skill
Enhanced Item +3
Deal Over 1'00 Damage
Reach Level 30
Defeat Prince of Madness
Have Over 150% ATK SPD
Reach Fusion Level 10
First Enhancement
Equip a blade and meet Kairon
Reach Level 10
Have over 3'00 HP
Do your first fusion
Defeat Xoreb
Reach Level 140
Reach Level 160
Reach Level 180
Reach Level 200
Defeat Githeon The Galactic Conqueror
Defeat Oreb and Zeeb
Defeat Dr. Congo
Deal Over 10'000'000 Damage
Have Over 1'000'000 HP
Have Over 10'000'000 HP
Defeat Error
Defeat Unlimited Error
Defeat Unlimited Nightmare Error
Made A Costume
Enhanced Item +20