We have got this down now I would say the tactics that matter.
1.) The tank on ignis needs to straffe the moment you see the jets that put the hot spot on ground. Ideally you are never in the hot spot or only for a minimum time to help minimize damage on you. You healers are easily able to heal you thru it but that assumes they aren't do other things and its so easy to move it makes the healers life alot easier.
2.) The add tank needs to not panic and assuming the MT is doing the above even having 2 or 3 adds up is not dangerous to MT's health. The key is to tank the adds and only make them molten when everything is under control. The adds hit alot harder when they are molten and drop agro so you need to have that process under control.
3.) All dps including range should follow ignis around being at his back. If a healer gets stuck in pot all the raid is still in range of healer and if the OT gets stuck in pot the MT can grab any lose add because everyone is within taunt range.
How many spots and where I find matters little if you use the above.
** Remember Warcraft players fail in directions you never thought possible.