Used by SCH in his stun set, this coat have both haste, that helps in reducing recast time, and macc, that help with stun in NM with high meva, or that get resistant of stuns over casts.
That being said, currently i would prefer hagondes coat than this. Hedera triumphs in the haste stats, have +2% than hagondes, but proper augmented, hagondes can double the amount of macc, not considering the INT already present in coat.
In solo stun situations, maybe 2% haste can be more important than extra macc, but in majority of situations, you will have 2 stuns SCHs hasted+marched. In that case, you dont even need alacrity to keep stuns in delve mega boss as example, but you DO need macc a lot more than haste if the fight takes longer than 8 mins.