Well, although I haven't defeated Fire Elementum, my friends and teammates supported me in defeating fire elementum. But I am too busy to play miscrits. So I will just tell u what my friends told me......
First of all, one of the factor of victory is LUCK. So, without luck, the Fire Elementum will gonna kill u in 1 hit with HELL FIRE. Hell Fire is similar to sinkhole when u are trying to defeat earth elementum.
here is the way.
1. U might need Lavarilla, Liquifien, Dark Firebrand, and azteko or some other miscrits that have MAX or ELITE stats on their attacks. For Lavarilla and Liquifien, enchant the final attack and unbreakable.
2. For Azteko, spam ENCHANTED Fortify until the elementum's attack is about 6-9. For Lavarilla and Liquifien, spam ENCHANTED Unbreakable till the elementum's attack is about 6-9. For Lavarilla, you need to buff physical attack because Fire elementum's physical defense is better than Elemental Defense. For Lavarilla and Liquifien, attack with ENCHANTED Overpower/Ancient Splash if you are low on health but high on defense. Because that attack will restore 15 health. Remember to keep your health in Red Zone or else the Fire Elementum will us HELL FIRE>> a 1-hit- K.O kill.
3. For Azteko, its easier. U just need to attack with ancient sands which damages the elementum by about 100..... But for Lavarilla and Liquifien, u need to buff ur attack with potions of buff ability.
4. Attack attack and Attack and the elementum will be DEAD.
I actually defeated all elementums EXCEPT fire, which is the HARDEST one. well, good luck for you all in defeating all elementums and apollo nox.
alternatively, you can use furfin or dillorock to defeat Fire Elementum. but i defeated it using liquifien. i will post on how to defeat apollo nox when i have time :)