Yet another Matrix spell

I have been toying with a trigger-based spell, I call it Temporal Velocity. The idea is that when the hero casts the spell, everything in the game is slowed down to 10% for 5 seconds, then put back up to normal speed.
I realize that I can only effect units (unless I'm wrong, in which case please let me know), but thats alright.
The actual ability is a modded War Stomp with no damage, stun, range, targets etc.

I set up this trigger:

EVENTS
A unit finishes casting an ability

CONDITIONS
Ability being cast equal to Temporal Velocity

ACTIONS
Pick every unit in Playable Map Area and do actions:
Set picked unit's animation speed to 10%
Set picked unit's movement speed to Picked unit's current movement speed / 10

Set casting unit's animation speed to 100%
Set casting unit's movement speed to Picked unit's default movement speed

Wait 5 seconds

Pick every unit in Playable Map Area and do actions:
Set picked unit's animation speed to 100%
Set picked unit's movement speed to Picked unit's default movement speed

-----------------------------------------------------------------------------------

For some reason, the trigger doesn't seem to work. It slows down animation a tiny bit (I'm guessing to about 90%), and movement speed goes to about 50%. But, that gives completely the wrong effect. I was going for enemies moving in slow motion as the caster moves and attacks normally.

If anyone knows anything about this, please let me know!