Here is the full list of all 54 Waitventure achievements.
Fuse 64 humans or monsters
Recruit a total of 50 allies in the dungeon
Using EXP/s upgrades, level up a character to level 2 in one second
Fuse 32 humans or monsters
Reach 1000 MP with one of your characters
Reach February in the Dungeon
Reach level 100 with one of your characters
Reach level 200 with one of your characters
Reach level 300 with one of your characters
Reach level 500 with one of your characters
Using EXP/s upgrades, level up a character to level 5 in one second
Using EXP/s upgrades, level up a character to level 10 in one second
Recruit a total 100 allies in the dungeon
Recruit a total 200 allies in the dungeon
Fuse 128 humans or monsters
Fuse your first S-rank monster
Fuse your first X-rank (or SS-rank) monster
Fuse your first Y-rank (or SSS-rank) monster
Fuse your first Z-rank (or SSSS-rank) monster
Have 4 S-tier monsters in your team
Have 4 X-tier (or SS-tier) monsters in your team
Have 4 Y-tier (or SSS-tier) monsters in your team
Have 4 Z-tier (or SSSS-tier) monsters in your team
Reach 500 ATK with one of your characters
Reach 1000 ATK with one of your characters
Reach 2000 ATK with one of your characters
Reach 500 DEF with one of your characters
Reach 1000 DEF with one of your characters
Reach 2000 DEF with one of your characters
Reach 500 SPE with one of your characters
Reach 1000 SPE with one of your characters
Reach 2000 SPE with one of your characters
Reach 2000 MP with one of your characters
Reach 5000 MP with one of your characters
Reach 2000 HP with one of your characters
Reach 5000 HP with one of your characters
Reach 9999 HP with one of your characters
Unlock by recruiting or fusing all humans
Unlock by recruiting or fusing all slimes
Unlock by recruiting or fusing all amorphous
Unlock all S-tier monsters in the Collection
Unlock all X-tier (or SS-tier) monsters in the Collection
Unlock all Y-tier (or SSS-tier) monsters in the Collection
Unlock all Z-tier (or SSSS-tier) monsters in the Collection
Complete the Collection
Reset the game 10 times
Reset the game 20 times
Reset the game 50 times
Reach June in the Dungeon
Reach December in the Dungeon
Beat a S-tier Big Boss
Beat a X-tier (or SS-tier) Epic Boss
Beat a Y-tier (or SSS-tier) Legendary Boss
Beat the Z-tier (or SSS-tier) Dungeon Boss