Crystal Trap

You empower a small gem or crystal with explosive energy, when you cast the spell and throw the crystal on the ground it then becomes charged.

If a creature comes within 5 feet of the charged crystal, the trap triggers, when triggered the crystal erupts with magical energy in a 5 foot radius 15 foot high cylinder centered on the Crystal. any creature in the area must make a Dexterity saving throw. A creature takes 4d6 damage on a failed saving throw or half as much damage on a successful one.

The damage type for this spell depends on what gem or crystal you use, if you use a diamond roll a d8 to see what the damage type is.

1 Ruby-Fire, 2 Sapphire-Cold, 3 Emerald-Acid, 4 Amethyst-Poison, 5 Topaz-Lightning, 6 Garnet-Psychic, 7 Amber-Radiant, 8 Obsidian-Necrotic 

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.