Manaburn from tinctures interaction with mana regeneration

The effect of manaburn is to lost 1% of your maximum mana per second per stack. As of writing I have 70 maximum mana (14 unreserved), 217.1 mana regen per second, so I should have more than 300% mana regeneration per second, which translate to be able to endure upto the same amount of manaburn stacks (300 stacks).

However in game, the tinctures turn themselves off (by getting mana to 0) only at ~220 stacks. In another note, it seems that the more mana you reserve, the few stacks of manaburn you're able to have.

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_Katastrophe wrote:

As of writing I have 70 maximum mana (14 unreserved), 217.1 mana regen per second, so I should have more than 300% mana regeneration per second, which translate to be able to endure upto the same amount of manaburn stacks (300 stacks).

Path of Exile: Settlers of Kalguur Recently Asked Questions in the announcements forum:

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Can I use items that lower my maximum mana combined with flat mana regeneration to sustain a very large number of Mana Burn stacks?

Yes, but only to an extent. Each stack of Mana Burn drains a minimum of 1 mana per second.

The drain can be countered by your regen, which is why you can reach such high stacks in the first place. But, above 217 stacks, the drain is greater than your regen, and your mana starts falling.

If that's the case then it's a bummer. Wish that crucial detail was present in the game instead of on the forums.

On the other hand, if I want to get higher stack count I should still be able to stack more regen number (400 regen I should be able to stack 400 manaburn)?