First Strike.

The reckoner has advantage on initiative rolls.

Spellcasting.

The reckoner is a 5th-level Boros spellcaster. Its spellcasting ability is Intelligence (spell save DC 12, +4 to hit with spell attacks). The reckoner has the following wizard spells prepared:

Cantrips (at will): blade ward, light, message, shocking grasp
1st level (4 slots): guiding bolt, shield, thunderwave, witch bolt
2nd level (3 slots): blur, levitate
3rd level (2 slots): lightning bolt

Actions

Longsword.

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) slashing damage, or 8 (1d10 + 3) slashing damage if used with two hands.

Reactions

Lightning Backlash (Recharge 5–6).

When a creature hits the reckoner with an attack, the attacker takes lightning damage equal to half the damage dealt by the attack.

Reckoner