Dinh's bulwark

Arraxor may not be a "spider", but with Jagex being Jagex, there's a significant chance that a lot of annoying small NPCs will still be a part of the encounter. Even if these NPCs end up not existing (let's say a 50% chance), even if Scythe is BiS, Dinh's can potentially be swapped into between hits to reduce damage (assuming prayer won't negate all damage, which is likely given the level requirement of the boss and yielding a new BiS amulet).

Furthermore:

* Has been steadily rising along with inflation * As close to a raid megarare as it gets (1/23 per CoX purple vs. 1/34.5 for Tbow/Kodai/Elder) - same rarity as Ancestral * Lowest cost/effort of all CoX uniques (excluding Arcane, which is a one-time unlock)

Assuming it ends up being useful at Arraxor, I could easily see it reach 30-40M+ mark due to rarity. Even if it's not, I don't see it dropping much due to its solid current utility.