Tiny Atomic Split v2

When casted, the caster takes time forming a ball of energy. However, this ball is mostly transparent and looks empty. This ball of energy is a containment field and takes 2 rounds to form. After these two rounds, a singular atom splits. This makes an extremely bright light acting like a beacon which can be seen through darkness and fog to a maximum of 30ft away as if they are looking at a mini-sun.

If you are attacked during round 3-4 and lose concentration, the containment field explodes and you take 2d10+10 force damage and 1d10 fire damage. Resistances and immunities to fire and resistances to force is considered null. Additionally anyone in 5ft rolls a DEX saving throw DC:15 or takes the damage as well. Everyone who takes damage falls prone and is stunned for 1 round. The caster however is incapacitated for 2 rounds.

On your fourth round, if you haven't lost concentration, pick a target you can see within 120ft of you or a place within range you can picture. You release this ball (which now looks like a mini sun) and shoots towards the target. The target, if wanting to dodge can make a DEX saving throw against your Spell DC to dodge take half "core damage" and are not prone.

Once the ball makes impact, the target or targets immediately within 5 feet of the blast take 5d10 force and 2d10 fire damage and are incinerated if killed outright, else fall prone. Those within 10ft of the "core" take 2d10 force damage and have to make a DEX save of DC:15 to avoid being knocked prone and take half damage. The explosion sound can be heard from over 1 kilometer away. Unlike a "premature explosion", this attack only nullifies resistances to fire and force including immunity to fire.

at higher levels, the spell damage increases by 1d10 damage to either force or fire for each level above fifth or increases outer AOE by 5ft.