The Fireblade spell increases your TAP damage by a factor of 3 for 30 seconds.
The cooldown on Fireblade, without Nanzuum Mana Cube, is 1 hour.
The Fireblade spell is unlocked when you get the Eyr Rune on your sword to level 5.
Causes the Runeblade to recall its Forging, making the blade burn with a scalding flame.
When your primary damage is from TAP attacks, Fireblade is your go to spell to help with Guardian encounters. Tripling your damage every time you encounter one should help make short work of them and get you moving forward again quickly.