Hecarim's R slow doesn't get reduced by slow resist

Hecarim's R fear slows enemies, same as all other fears. What's different about this one is that it doesn't get reduced by slow resist, while the slow of other fears gets reduced.

Procedure:

1. Have boots of swiftness
2. Proc phase rush
3. Get hit by hecarim R
4. See that you get slowed by it even though you have 100% slow resist