Bloodstar

You create a magic construct called a bloodstar that shoots from your hand and hovers in the air anywhere within the limit of the range (each round, you can move the bloodstar 30 feet with an action). The bloodstar pulses with ruby light (providing bright light in a 20-foot radius). When any creature within 10 feet of the bloodstar that takes damage from any source that creature must make a constitution saving throw. On a failed save, the receives twice as much damage from that source as it would normally. Each time victims are damaged, they can attempt new saves. On a Successful save the creature is immune to the effect of the bloodstar for 24 hours.  The bloodstar has an AC of 20 and 20 hitpoints and if it has to make a savingthrow it is treated as though it hand a 10 in all stats. 

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, increase the hitpoints of he bloodstar by 5 for each slot level above 4th.