Charms will drop randomly (as with everything else in this game) during your dungeon run. They provide a temporary effect for your character. You cannot equip more than one charm at a time, so in order to use five charms in the same run, you'd need to be lucky enough to find five of them, and ensure that each time you find one, you use it.
To use a charm, press
when you've it.
Charms drop pretty regularly to be honest, but if you want a higher chance of finding five in one run, consider using levels that have three to four floors. I was able to do it in a dungeon with only two floors though.
The list of charms are as follow (from childrenofmorta.gamepedia.com):
Black Foot - Increased move speed and dodge chance at the cost of being unable to evade.
Bloodstrike - Increased primary attack damage at the expense of decreased maximum health.
Brooch of Insanity - Greatly increase critical hit chance and damage at the cost of a slow, constant drain of health.
Cursed Potion of Life - Increased maximum health at the expense of decreased primary attack damage.
Divine Gift - Drop a divine item.
Essence of Finesse - Increases movement speed.
Essence of the Obelisk - Gain the effect of a random obelisk of Morta.
Feather Pin - Increased dodge chance.
Ferocious Token - Ferocious enemies do reduced damage.
Gemstone Wrapping - Drops a gemstone.
Greater Gemstone Wrapping - Drops three gemstones.
Health Potion - Restore a portion of your maximum health.
Hearty Invigoration - Temporarily increase rage gain.
Potion of Life - Increased maximum health.
Reckless Precision - Increased critical hit chance.
Relic Slot Machine - Reroll all Divine Graces.
Ring of Ambition - Corpses have less chance to get corrupted and spawn enemies.
Ring of Regeneration - Constant health regeneration, health globes heal less.