Here is the full list of all 26 Transcendence Legacy - there are Voidswept achievements.
Defeat the Mist Crawler.
Defeat the Holy Knight.
Defeat the Kraken.
Defeat the Dark Knight.
Defeat the Gatekeeper.
Defeat the Gargantuan Thorns.
Defeat the Regal Dragon.
Defeat the Gleaming Serpent.
Defeat the Grim Revenant.
Defeat the Greater Mimic.
Defeat the Green Haired Swordsman.
Gift Yellow Rose to Clymene two times.
Gift Yellow Rose to Schar two times.
Gift Yellow Rose to Celina two times.
Gift Yellow Rose to Zion two times.
Gift Yellow Rose to Revouger two times.
Fully upgrade the Blacksmith.
Fully upgrade the Skill Shop.
Pet the cat 100 times.
Pet the dog 100 times.
Defeat the final boss.
Defeat the final boss on Expert difficulty.
Start a New Game+.
Defeat the Proto Angels.
Defeat the Proto Daemons.
Sit down. That's... pretty much it.