It’s clear that this is meant to be somewhere between “MOP-era Ranged Survival” and “HotS Sylvanas” for the inspirations. If that’s true, then there’s a few places they can improve upon this… in my opinion. Goal is to minimize the number of GCDs we’re forcing on the rotation.
First, provide a passive with Black Arrow that replaces Arcane Shot (MM) or Cobra Shot (BM) with Withering Fire, which deals Shadow damage.
Second, have Black Arrow’s proc make your next Withering Fire shoot three times. BM doesn’t want even more Barbed Shot resets, and the Aimed Shot charge that isn’t instant-or-free is… kinda unnecessary or clunky? This plays into the old Explosive Shot being “three Arcane Shots in a trench coat.” Each shot consumes Precise Shots as normal, so it’s a quick way to offload stacks when available.
Second, change Dark Empowerment to make Black Arrow empowered Withering Fire cost no focus. It’s no longer resetting abilities, so… yeah.
Third, replace Dark Hounds with a talent that interacts with Wailing Arrow. Perhaps “your autoattacks against targets affected by Black Arrow reduce the cooldown of Wailing Arrow by X seconds.” Hunters kinda hurt for AoE stops that don’t chuck enemies across the world in M+, but this also plays into Readiness for Raid for MM. Unfortunately, this doesn’t do as much for BM.
Fourth, have Shadow Surge apply a 6s Shadow damage DoT to enemies hit, no CD. Play into the old Serpent Spread: what made it fun was the uncapped DoT application. This also is similar to HotS Sylvanas’ Shadow Dagger, which applied an AoE DoT! Put a DoT on your primary target, and watch it spread to the neighbors. The 6s duration means that just spamming Multi-Shot doesn’t provide a ton more damage, as you’re just refreshing the DoT, but does mean you have a bit more flexibility with when you cast (Pandemic window means you can be a bit early). Reasonably, this should also increase Beast Cleave duration to match.
Fifth, replace current Withering Fire with Might of the Banshee: dealing damage with Withering Fire applies a Curse to the target. At 3 stacks, your next Aimed Shot / Barbed Shot or Kill Shot consumes the stacks to deal bonus Shadow damage. This is based on a combination of Sylvanas’ passive in HotS and, ironically, her level 7 talent “Barbed Shot.” It’s a bit more active than the dark arrow barrage, and that “fantasy” is already covered by the Withering Fire multiattack. But it plays into the “assassin” nature well.
Ultimately, I find it really hard to make anything here actually BM themed at all. However, by making Withering Fire an upgraded Cobra Shot for them, the extra shots give bonus CDR from Cobra Senses, buffs the free KC chance from Cobra Sting significantly, etc.