Volcanic Geyser

You spread your arms slowly from your hips to your chest meanwhile creating a ball of lava behind you. You can keep winding this spell up to a minute and for each round that passes while you maintain concentration the ball increases in size and so, effects. If you fail to maintain concentration the lava ball is reduced to nothing instantly. When you decide, you throw the ball of lava to a target you see within range which then explodes into flames and molten rock. Everything in an area of (5 * rounds winded)-foot-radius sphere will take (3d6 + rounds winded * d6) bludgeoning damage and (3d6 + rounds winded * d6) fire or half of that on a successful DEX saving throw. The lava thrown will remain in a circle of the same radius as cast for (1 + rounds winded) round and the ground in that circle will be considered difficult terrain and whatever ends it's turn in there will take 2d6 fire damage. After which time the lava will have been hardened and so the ground will lose the effects described before. You may not use any actions or reactions while winding up this spell.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, both damaging effects increases by 1d6 for each slot level above 4th.