Do reactions use spell slots in 5e?

How do Spell Slots work in D&D 5e? does hellish rebuke use a spell slot use spellcasting alongside martial attacks, such as battle Hellish Rebuke is particularly useful for spell slot-strapped Warlocks does ritual casting use a spell slot @caborn46Can a spellcaster use a reaction spell and cast a spell in the same turn for his action?

does s21 ultra have s pen slot They are always cast at the highest possible level So at level 3 most full casters have four 1st level spell slots and two 2nd level slots,