Investiture of Flame

6th-Level Transmutation
Casting Time: 1 bonus action
Range: Self
Components: VS
Duration: (C) 10 minutes

As in Xanathar's Guide to Everything except it is a bonus action to cast, the line of fire has been increased to 30 foot long from 15 foot long, it activates on cast and as a bonus action on subsequent turns, and the following has been added:

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the damage of the spell’s effects increases by 1d10 (for the second effect) or 1d8 (for the third effect) for each two slot levels above 6th.

Source: XGE 159

Changelog

Altered range of the action line of fire to 30 foot long from 15 foot long.
Added upcasting option.