How do Spell Slots work in D&D 5e?

does hellish rebuke use a spell slot   Dan does slot open on sundays

You point your finger, and the creature that damaged you is momentarily surrounded by hellish flames The creature must make a Dexterity saving

Similar to Hellish Rebuke, it is a good melee spell But this one does not use a spell slot, making it somewhat more cost-efficient  When you do this, the level you cast the spell at is the spell slot it eats up Say you power up a level 1 spell to cast it as a 3rd level spell

demo slot zeus olympus Remember Cantrips do not use spell slots, and Warlocks in particular have You leave your spell slots for Hellish Rebuke, which will provide a reaction  When you do this, the level you cast the spell at is the spell slot it eats up Say you power up a level 1 spell to cast it as a 3rd level spell