"Don't get too close," is the only thing Gregory says to the archons before launching into his spell.

The two lantern archons fly 60 ft. away from their initial positions, up and at an angle, toward the abomination. Then they shoot rays of light at it.

Spoiler: Mechanics
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The lantern archons have perfect flight, so if my calculations are correct, they can move to 24 on the map and be 40 feet above the ground. That's straight diagonal movement. They start taking potshots at it from there -- with its space, that should be within their 30 ft. range.

Lantern archon 1 light ray ranged touch: (1d20+2)[6]; damage: (1d6)[4]; confirmation if crit: (1d20+2)[13]; crit damage: (1d6)[1]
Lantern archon 2 light ray ranged touch: (1d20+2)[11]; damage: (1d6)[1]; confirmation if crit: (1d20+2)[19]; crit damage: (1d6)[2]

Gregory's current HP: 98/196