Conjure Blood Elemental

When you cast this spell, your current hit points are reduced by an amount equal to the spell's level.

You call forth an elemental servant. Choose an area of spilled blood that fills a 5-foot circle within range. A blood elemental appears in an unoccupied space within 10 feet of it, emerging from the blood. The elemental disappears when it drops to 0 hit points or when the spell ends. The elemental is friendly to you and your companions for the duration. Roll initiative for the elemental, which has it's own turns, and it takes only the actions you want it to take (no action required by you). If your concentration is broken, the elemental is destroyed.

The elemental uses the statistics of a Water Elemental (pg 125 of the Monster Manual) but is immune to necrotic damage instead of cold damage, and does not have Aquan as  a language.