Hey there !
Leveling a ranged elem purifier ATM, and while expecting RR need in higher level I started playing with thermite mines.
And…well… that’s annoying. Mobs keep moving, mines never fall the way I want and range is laughable.
It is mandatory for an elem purifier? I took the viper and the crown, but the latest is flat reduction so it doesn’t stack.
Am I “forced” to use those damn mines?
you can use solael witchfire devotion, it is nice and spreads nice.
but yes, mines are unfortunately a must. No idea how long reisist removal works after monster got hit by it. 1 second, 2 seconds? no idea
Yeah solael is fine, but is only fire 
Unfurtunately Ranged Purifier made to attack in close range with a static position by it’s skills like Mines, Seals and AoC(It’s range isn’t that wide either)
damn, that sucks. I wanted to make a long (erm) range pistol thingy, not a close combat pistolero.
You can convert the character over to a Pierce Valdun rifle user later to take out Thermite Mines and Censure but Inquisitor’s Seal still gets used. You could also take that out if you don’t mind missing a decent chunk of defense but for the harder kinds of end game content, you really want as much as you can get your hands on.
I haven’t played Purifier or used Thermite Mines yet, but whenever somebody tells me something “is a must”, I actively avoid choosing that thing. Still I make my way through the game having fun. Just saying.
Don’t like them 
don’t use them. You’ll be fine.
A must is not the complete way of phrasing it. Someone could make an Elemental Purifier without Thermite Mine or Censure and play through the game on the lower difficulties like Normal/Veteran.
As you progress through the mid and higher difficulties though, the need for the skills I mentioned increases as enemies gain more health and resistance. Sure you could still not use them but anyone that does so then has to understand that they are making the choice to avoid some of the best ways of increasing their damage output against enemies that are balanced around with the idea that players are using these damage increasing abilities in mind, thus kill times and even survivability are likely to be lower than other Elemental Purifiers.
It’s not a perfect system and has been criticised that to play optimally or on the hardest difficulties that a section of skills in every mastery are “necessary” and characters/the game are balanced with them in mind but it’s just how things have developed. Arguably, it’s no different to other ARPGs or RPGs out there with regards to playing on the hardest difficulties for them as well.
At least you have this part right though 
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Personally I don’t mind the updated mines (their QoL was increased in some patch). I feel like one batch of them covers a pretty good area. They also have a very quick animation. But yeah, Fire Purifier is not a long range but a mid range character.
Wait, your mines still fall?
You play the latest patch, right?
Yeah, “fall” might not be the word, you’re right. “Pop” maybe? 
No brainer not to use Mines for RR, for good or bad RR is essential mechanic. You can avoid using it but you shoot yourself in the leg. Lower RR means low damage output again resistant enemies, that’s hardly “fun”
To @ChaK even if Purifier is the best class for ranged, you can try other classes without mines, Tactician can use Cadence + Censure for RR. Fire Paladin with Censure+Guardians. Acid Dervish or lightning Primal Strike Vindicator are also possible. Actually Vindicator is the second best option for leveling ranged and visuals are cool as well.