Welcome to DQ Forums @Krazi !
you can have 0, 1, or 2 affixes and 4 Socket on an Item when making a Mythic affix.
some affixes can only be found on Items. here’s a post to help.
the Crushing Flames Bonus gives 400% damage to Immolate. Immolate increases Fire DoT +100%. normally, Fire DoT is 40% of Fire Attacks damage every second for 2 seconds. Immolate would be 80%. with CF Bonus, +100% + 400% is +500% or 6x so Fire DoT 240% of Fire Attacks Damage every second for 2 seconds. CF (5) increases Immolate +125% damage so umm… Fire DoT 540% a second for 2 seconds. with one Immolation +50% on top of all that… Fire DoT 810% of Fire attacks damage every second for 2 seconds.
Crushing Flames can be rolled with Amethyst. if you don’t want to have to get CF again, then take the other 3 affixes off and add 3 Sockets to make Brutal. if you want your Immolate to tons more damage, keep Immolation Damage and take off CF and the other 2 affixes and make Brutal. if you don’t want the CF Bonus, use some other Chest Item and put CF on it, or use one of the other CF Items.
Main attack - do you mean Meteor? Special Skills like Meteor on MH or Shatter on OH can be changed with Amber. it gives you 3 random choices of Special Skills from the MH Pool for MH & OH Pool for OH. if you mean Comet, then no.