Here is what I’ve figured out so far.
D - Defeat a green 6* Shiva 10 times (Stage 10 of the Words “D*” roadmap has 3x green 6* shiva)
E - Spend 100 energy total - World energy is easiest
P - Use 10 “Hollow Point” rounds in battle (it’s a battle item that looks like 3 bullets).
U - Upgrade a toon to their next tier - 2* worked
T - Train toons via training grounds - 2*'s worked.
Y - Level up a yellow toon 20 times.
Edit: Part 2 is here: Last Words - Part 2 - Solved