When you use a spell slot to cast a spell that deals Fire damage, you can expend the Charm (no action required) to treat the spell as if it were cast using a spell slot 1 level above the slot expended.
Manifest Charm of Fernia, the Sea of Fire
RewardEFAp. 502024
Raw data
{
"name": "Manifest Charm of Fernia, the Sea of Fire",
"page": 50,
"type": "Charm",
"__prop": "reward",
"source": "EFA",
"entries": [
"When you use a spell slot to cast a spell that deals Fire damage, you can expend the Charm (no action required) to treat the spell as if it were cast using a spell slot 1 level above the slot expended."
]
}