Thunder Snake

You trace a thunderous storm sigil in the air (either with your hands, a wand, or a staff), summoning a stormy snake made of concentrated lightning and thunder magic in an unoccupied space you can see within 15 feet of you. When the snake appears, you choose a direction for it to face. Flip a coin; If Heads, the snake whips the tip of it's tail up to 15 feet in a straight line and makes a melee spell attack against the first creature it encounters in that line, dealing 1d12+3 thunder damage on a hit. If Tails, the thunder snake fires out a breath of lightning in a 15 foot straight line from where it is dealing 1d10 lightning damage to anything within that 15 feet line. The thunder snake dissipates immediately after the attack. The thunder snake is a magical effect and not a creature.