HIVE

There is no tutorial, but it's not really complicated. All you need to do is periodically select the affected units and change their speed.
The reason I put the units into an array before this is that this way the system runs much more efficiently.

Dam. Haha, not complicated for you maybe... What triggers should I use to select the units and what triggers do I use to change speed? How do I set up the array?

Or could you give me a sample trigger?

I don't really want to bother with samples. I can only describe.
Bribe's unit indexer has events for when units appears and disappear. You can use those. The exact method is written here: https://www.hiveworkshop.com/threads/gui-unit-indexer-1-2-0-2.197329/
(Look at the part called "How to take advantage of UnitIndexEvent")

For the way that I stored units in an array look at this: https://www.hiveworkshop.com/threads/visualize-dynamic-indexing.241896/
It's a pretty standard way.