Phase Spider is a Large monstrosity with unaligned alignment and Challenge Rating 3 in the 2024 SRD. This stat block includes AC 14, 45 hit points, speeds, traits, and actions.
Multiattack - The spider makes two Bite attacks.
Bite - Melee Attack Roll: +5, reach 5 ft. Hit: 8 (1d10 + 3) Piercing damage plus 9 (2d8) Poison damage. If this damage reduces the target to 0 Hit Points, the target becomes Stable, and it has the Poisoned condition for 1 hour. While Poisoned, the target also has the Paralyzed condition.