So it is. My mistake, I meant Call Lightning, which is third level. AoE *instant* spells aren't the tool for the job. AoE *duration* spells are the better artillery equivalent.
If, for some reason, a) you're in a situation in which all 100 of them can fire directly at you (which means you're not properly using all your sensory and mobility advantages), and b) the occasional hits are somehow more than a curable annoyance despite your False Life, your paladin buddy's Aura of Vitality, etc., then use Hunger of Hadar instead. Their first rank isn't gonna deliver aimed arrow fire from within it, nor can the ranks behind them, since it blocks LOS. Follow up with cantrips, because the side with infinite ammo has an advantage in a battle of attrition by mutual blind fire.
It's not just the hobgoblins you can zap *on the first round*. It's how many every round, for the spell's duration, and the morale effect. Moonbeam, Call Lightning and Hunger of Hadar are *at least* as terrifying as a modern mortar barrage. When you incinerate 10% of an attacking force, the remaining 90% notice. Units which keep attacking after 25% casualties are notably stubborn. If you were hobgoblin #26, in a force which numbered 100 a minute ago and is now down to 75... would you feel lucky?
Sure, you play your other cards too. Your AoE-Duration spells prevent them from using close formation, and thus your warrior allies can mop them up in detail, and so forth. AoE-Duration spells are still game-changers against horde foes which can't survive 2d10 damage; much more so than Wild Shape, Action Surge, Sneak Attack, etc.