Question about Gloria.

Is it a good idea to get Gloria if I already have 250 DEF & MDEF?

 

You can just tag me for such questions.
And Lvl5 gloria can cancel the nega of reflex.
It gives highest reduction at 3 points when:-
You have 84def/mdef (which you wont if you equip any sort of armor) [14% damage reduction after gloria]
You have 416def/mdef [11% damage reduction after gloria]
You have 8194def/mdef (Try getting that value) [99.99% damage reduction after gloria]

 

As Mayam stated, 250 is the mathematical limit for the Def / Mdef curve (in terms of cost vs effectiveness).

Using the math left by Mayam, 250 Def is that of 0.8% damage reduction for every 10 Def, therefore 250 Def is 20% damage reduction.

(250 / 10) * 0.8% = 20%​

From then until 1250 Def, every set of 100 Def is equivalent of 1% damage reduction.

Since Gloria triples your Def, your ending Def will be 750. The extra 500 Def beyond the initial milestone of 250 Def will give you this much reduction:

(500 / 100) * 1% = 5%​

Given your already granted 20% damage reduction from your initial 250 Def, Gloria will provide you with only a measly 5% extra damage reduction.
​

Mathematically speaking, it's not worth it, if you already have 250 Def.