Elstren's Chain Lightning Blade

You brandish the weapon used in the spell’s casting and make a melee attack with it against one target within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects along with 1d8+your spellcasting ability modifier lightning damage, and you can cause lightning to leap from the target to a different target of your choice that you can see within 10 feet of it. the new target takes 1d8+your spellcasting ability modifier lightning damage, and you can cause lightning to leap from the target to a different target of your choice that you can see within 10 feet of it. The new target takes 1d8+your spellcasting ability modifier lightning damage

At Higher Levels. When you cast this spell using a spell slot of 2th level or higher, the number of targets increases by 1 for every level higher (example example at third level you can chain five targets)