Here are some name suggestions for your chestnut paint Icelandic x Thoroughbred mare, reflecting her energetic nature and mixed breed:

Emphasizing Energy & Spirit:

• Ember Blaze
• Firestorm
• Rhapsody
• Spitfire
• Quicksilver
• Wildfire
• Comet
• Aurora
• Hurricane
• Zephyr

Highlighting the Paint Coat:

• Painted Lady
• Chestnut Comet
• Auburn Flash
• Copper Sparkle
• Sunburst
• Honeycomb
• Caramel Kiss
• Red Velvet
• Spotted Shadow
• Painted Dream

Reflecting Icelandic Heritage:

• Freyja's Fire
• Valkyrie's Blaze
• Skuld's Spirit
• Astrid's Grace
• Runestone
• Glacier's Glow
• Midnight Sun
• Northern Lights
• Icelandic Dream
• Viking Spirit

Combining Elements:

• Painted Valkyrie
• Ember Runestone
• Firestorm Freyja
• Rhapsody of the North
• Auburn Valkyrie
• Copper Comet
• Sunburst Skuld
• Honeycomb Hurricane
• Glacier's Spitfire
• Viking Blaze

More Creative & Unique Options:

• Phoenix
• Seraphina
• Luminary
• Celestia
• Elowen
• Isadora
• Aella
• Lyra
• Nova
• Renegade

Remember to choose a name that you feel best represents your horse's personality and appearance. Consider saying the names aloud to see how they sound and feel.