This tutorial will show how to create a fire text effect! All the details of each step should be the default settings unless it says otherwise. For this tutorial you will need Layer Effects(only inner glow) and G'MIC.
1. Add Text
2. Script-Fu > Layer Effects > Inner Glow (Orange, Opacity:100, Size 20)
3. Back to text layer repeat step 2 with Yellow and Size 10
4. Move Yellow Inner Glow layer to the top
5. Merge Innerglow layers with text layer, Change bottom layer to black
6. Filters > Light & Shadows > Drop Shadow (Red, Blur Radius: 20)
7. Duplicate Drop Shadow Layer 2 times and turn off visibilty on all other layers, merge visible layers
8. Go to FIRE layer and IWarp the edges of the text with radius 15 and amount .15 Swirl CCW
9. New Layer...Filters > Render > Lava
10. Duplicate Layer and set layer mode to Screen, Merge Down
11. Duplicate Lava Layer
12. New Layer fill with yellow set layer mode to Hue, merge down
13. Filters > Distorts > Value Propogate (more white)
14. Turn Visibility off on bottom 3 layers
15. Go to GMIC > Layer > Negation (Change Input Layers to All Visible)
16. GMIC > Deformations > Water (Smoothness 2.5)
17. Add Layer Mask and erase where the text is using the airbrush tool so it still shows some flames
18. Colors> Brightness Contrast (Brightness:10 Contrast:20)
19. Filters> Map> Displace (X:10 Y:10)
20. GMIC> Colors> RGB mixer (Red Contrast 1.3, Red Brightness 54)
21. Flatten Image