Area Of Decay

You create an area, centered around a point that you can see where all life gets sucked away and where everything starts to rot, rust and crumble until there is just a barren area left.

Any creature with a physical body (exept undead) entering the affected area or ending it's turn in the affected area take 5d10 necrotic damage and have disadvantage on all attack rolls & Constitution saving throws.
Creatures killed in this area become eather a pile of bones & rotting flesh if they are living creatures or a pile of rusting metal / rotten wood / ... if they are a Construct / item.

If this spell is cast every day for 30 days in the same location, the spell lasts until it is dispelled, and the material components are consumed on the last casting.
When you cast this spell, you can designate a password. A creature that speaks the password as it enters the area takes no damage from the spell.

At Higher Levels. When you cast this spell using a spell slot of 6rd level or higher, the spell does an extra 1d10 necrotic damage  for each slot level above 5th level.