1. ALL spell cast speed reduction spells. Biggest ones including: https://wowwiki-archive.fandom.com/wiki/Snake_Trap https://db.pandawow.me/?spell=73975 and https://db.pandawow.me/?spell=5761 (Shiv effect = -100%)
2. Apparently all spell cast reduction abilities reduces the player's haste by the percentage completely. For example, snake trap is -30%, if a caster obtains this, his haste is SUBTRACTED by 30%, effecting ALL global spells and Global Cooldown SPEED, not just SPELL CAST spells.
3. It should reduce strictly a spell that is casted, if not, it should at least reduce the CORRECT percentages. It was not like this in the past.
4. 11/9/2021
5. Realm : Fun
6. 9/10
Proof : https://streamable.com/gr52z6
https://streamable.com/hd6j7w
Proof in the past of how it SHOULD and USED to work, this was a 1v1 que arena season 9 on 5/25/2019 on Pwow Fun server (https://cp.pandawow.ru/en/armory/pvp.html?guid=6257260&realm=3&type=4&season=9), notice how only the SPELL CAST speed is reduced and not GCD HASTE speed for ALL instant cast spells: https://streamable.com/av59pe