This bomb, commissioned by Prosper from engineers in Cumberland, takes 100GP in materials and 3 successive skill checks to safely assemble (1 - DC 15 INT, 2 - DC 18 Slight of Hand, and 3 - DC 18 Arcana)
Once assembled correctly, the bomb is highly volatile, and will react to any spell cast at least 4th level in its vicinity and must succeed on a CON save (+0). This effect is mitigated if the bomb is kept in a demiplane such as a bag of holding
4-5th - DC 12
6-7th - DC 15
8-9th - DC 18
To detonate, hit the bomb with an attack spell (roll to attack or AoE) at 4th level or above. The bomb takes 1 round (6 seconds) to explode - casting Dispel Magic on the bomb diffuses it and makes the spell level required to detonate it after increase by 1. The damage caused by the bomb decreases by distance.
1st circle (20 ft diameter)- 10d10 (Dex save 20)
2nd circle (40 ft diameter) - 5d10 (Dex save 17)
3rd circle - (60 ft diameter) 2d10 (Dex save 15)
Chain Reaction
Any arcano crystals within the first circle will automatically explode - in the second and third circle they must pass a CON save with the same DC as the players' DEX save (+0 modifier)
NOTE: If the spell to detonate the bomb is 6-7th level, crystals in the second circle auto fails and explodes, if the spell is 8-9th level, crystals in all three circles auto fail and explode - setting off a new chair reaction.
Notes: Damage: Force, Damage: Force, Damage: Force