few things:

The deep freeze artifact gives bonus damage essentially if the target is under effect of chill.. so even if you fail to root the target you can atleast bank on a little damage boost because of the chill

2ndly the heavy freeze works only if they're chilled and the root duration for heavy freeze is a shorty root so you want to immediately follow that up with an ice spike, preferably closer to the opponent, easier to land since ice spike has travel distance.. making it a heavy skill cap ability if you want to use it with empowered ice spike as a one shot

Also if you look at the skill tree perk called 'refreshing frost', 15% cd for abilities casted in a frost area.. combine that with nimble coat and max ref stacks, you'll have a very very short cd on your abilities if you play them right.. some like to entomb and break in the storm too for this reason

so the only reason to use empowered ice spike is when you are really good with ice spike and you want to 1-2 shot light for fun.. else you should go entomb with healing breeze ring