Bloodheart Stake.

The impaler is magically bound to the ceremonial stake and the sacrificed corpse the ritual caster used to create it. If the impaler is reduced to 0 hit points, it disappears, then re-forms 1d8 hours later in the nearest unoccupied space to the stake and regains all its hit points. The impaler dies only if it is reduced to 0 hit points while either the ceremonial stake is removed from the sacrifice's corpse or the impaler is on a different plane of existence from that corpse.

Legendary Resistance (3/Day).

If the impaler fails a saving throw, it can choose to succeed instead.

Actions

Multiattack.

The impaler makes one Spike attack and two Wicked Spear attacks.

Spike.

Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 15 (2d8 + 6) piercing damage, and the target's speed is halved until the start of the impaler's next turn.

Wicked Spear.

Melee or Ranged Weapon Attack: +11 to hit, reach 10 ft. or range 20/40 ft., one target. Hit: 13 (2d6 + 6) piercing damage plus 13 (3d8) necrotic damage.

Spike Burst (Recharge 5–6).

Twisted, spectral spikes shoot out from the impaler's body. Each creature within 30 feet of the impaler must make a DC 19 Dexterity saving throw, taking 40 (9d8) force damage on a failed save or half as much damage on a successful one.

Legendary Actions

The relentless impaler can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The relentless impaler regains spent legendary actions at the start of its turn.

Speed Spike. The impaler teleports up to 30 feet to an unoccupied space it can see. It can then make a Spike attack.
Deepen Wounds (Costs 2 Actions). Each creature whose speed is currently reduced by the impaler's Spike attack takes 18 (4d8) necrotic damage.

Relentless Impaler