You create a glowing dart of magical force. The dart hits a creature of your choice that you can see within range. A dart deals 1d4 + 1 force damage to its target.  When the dart hits, the target must make a CON save (Using Spell DC, Each Higher Level Increases the DC by 1 {First Increase is By 2}) The darts all strike simultaneously, and you can direct them to hit one creature or several.

At Higher Levels. When you cast this spell using a spell slot of 1st level or higher, the spell creates two more dart's for each slot level above 1st.

Can be used as a Reaction, this was built for Zert, Who is a support caster, and Normally treats it like a readied action, while he surveils the battle field, deciding who needs what help. 

DM's, Decide if it is a readied action, or reaction for your players, as a pure reaction it can cause combat to be unbalanced.