Warning: Once you wield this item for longer than around 30 seconds, it will have the word (deg) added to its name and it becomes untradeable. Using this item in combat adds the (deg) to its name instantly, also rendering it untradeable.
The Corrupt zuriel's staff used to allow a player to autocast Ancient Magicks spells or elemental spells, however this function is now obsolete. It would also unlock the Miasmic spells from the Ancient Magicks spellbook, which, if successful, lower the foe's Ranged and Melee attack speeds by 50%.
As an hour contains 6000 ticks, there are 1500 ticks in a 15 minute period and a magical spell is able to be casted once per 6 ticks when using a staff, you are able to cast up to 250 combat spells with this staff before it degrades. Thus, each spell costs approximately an extra 343 when using this staff, in addition to the runes that have to be used.
Previously Miasmic spells could be cast on NPC's, however it did not slow down their attack speed.
Although there was an updated version of the staff in the teaser pictures for the updated Zuriel's armour, the staff wasn't updated along with the armour. This may be unintentional, like with the Void knight deflector and Full slayer helmet(now fixed) and may be fixed later on.
A silhouette of the updated Zuriel staff could be seen on the bonfire banner on the RuneScape homepage. The specific reason for this is unknown, but it may be a spoiler of the Zuriel staff being updated in the near future.