cassirinir's obelisk of pain

The caster targets all creatures in a 10 foot cone. The caster can choose 3 exclusions, such as allies, pets or hostages. Targeted creatures must succeed on a DC 25 constitution saving throw or take 20d10 necrotic damage, taking no damage on a successful save.

After targeting the creatures, creates a pillar that is 30 feet tall & 10 feet wide. the pillar can be placed in anywhere in a 100 foot spere that the caster can see (the pillar must be conjured on the ground). The pillar is 10 feet wide & 70 feet tall. This radius is increased by five feet for every unsuccessful con save. The radius is decreased by 2.5 feet for every successful con save. The radius is increased by 10 feet for each kill. Every 10 unsuccessful save grants the user the ability to create 1 more pillar that is half as big & cannot be added to. Casting this spell again does not allow the caster to upgrade the first pillar.

The pillar lasts for 1 minute & does 3d6 necrotic damage each round to any creatures within 10 feet of it. damage increases for every 2 creatures hit with first attack by 1d6. any creatures who start their turn within 5 feet of the pillar must succeed on a dc 18 dexterity saving throw or be grappled & take double damage from the aura that the pillar emits