It’s not because of Assured Safety.
If you’re going Oracle on Disc (you shouldn’t, this tree is so much worse than voidweaver for them, which I’ll get into), you’d take Prayer of Mending and you’d cast it. Basically gives us both our regular PW:S casts, but also each PoM cast also casts PW:S at a lower value.
From disc POV of Oracle 2.0
This is just a terrible tree in comparison to Voidweaver. Voidweaver buffs all of our core spells - it makes all Shadow Covenants more powerful by just giving us a shadow AoE during it, it turns smite into a shadow spell like our tier set, it gives us a more powerful sfiend/bender, it makes SW:D proc fiend/bender (which means more Scov), etc, etc.
Oracle gives us pretty much nothing.
Premonition sounds like it’s still kinda clunky to play around. If it’s not off the GCD it’s pretty much a non-starter. The bonuses it grants disc are to PW:S, which isn’t BAD, but isn’t great, and it gives us access to PoM - which we’d previously never want to cast.
But that’s about it.
The different premonitions aren’t even great for disc besides piety maybe:
- Premonition of Piety
- This sounds OK, but honestly our burst heal in raid has traditionally been high enough that I don’t think this would grant us much, since we tend to be overhealing everyone. It’d definitely be OK, but honestly I doubt it’ll help much.
- Premonition of Insight
- This is again, OK? Really what this would grant us is like, double penances or double PW:S/PoM? This is a FAR cry from just getting the Voidweaver’s entropic rift though. We don’t have any short CDs that this is super useful for because our gameplan is to reduce the CD of bender anyway.
- Premonition of Solace
- This is pretty much terrible. I can think of few times I’d want to be ST focus healing as a disc priest outside of an emergency, and I’m not about to drop a 1 min CD to make it marginally more powerful.
That said, what I really want to highlight is JUST HOW BAD the comparison between both options are for Discipline
So:
- Power Word Shield
- Oracle buffs this spell by 10%, and allows PoM to proc it at much lesser strength. It also lets PW:S proc 1 stack of PoM.
- Voidweaver buffs this spell by 20% baseline, and after you use a mind blast, and additional 80% buff.
- Atonement
- Oracle gives you a 1 second duration increase. You can also spread it a bit more efficiently with Waste no time, and if you have piety up the overhealing will distribute itself.
- Voidweaver buffs atonement by 25% for 15 seconds after using mind blast (so 60% uptime).
- Premonition/Entropic Rift
- These aren’t 1 to 1 comparable, but it’s worth considering that every time Entropic Rift is up, it is doing Atonement healing for Disc (and increasing it by 25%) Wheras Premonition’s best case is redistributing overhealing.
- But that’s not all! Look at their uptime:
- Premonition is up for 10s every minute. So ~16% uptime.
- Entropic Rift is up for 15s every 24s. So ~62% uptime.
In a PvE setting, for a Disc priest to ever consider this tree, whatever the under construction talents are (the t3s) would need to be very attractive.
In PvP I also don’t think this is super great either, FWIW.