Paradox can silently heavy melee immediately after ulting.

[clamdoloribus]

To replicate:
After casting and landing ult, hold the melee key while switching places with the enemy.
No sound nor the normal heavy melee vfx accompanying it.

 

[JeffGeneral]

I have seen this in videos as an additional combo to the swap. No sfx and vfx is an issue though.

 

[Lagi]

Similarly, Pocket can do the exact same thing while in Satchel. Just enter Satchel, hold the melee key, and either let the duration end or cancel it early with space (or your preferred cancel key).