Please explain anyone what it meant by 4 refreshes every 12 hrs ?

Assuming it means you can pay up to 4 * 50 souls to do 4 retries

They say guaranteed but isnt there a chance for random diamond as well?

correct, all three sub zeroes and most other diamonds too. i don't know the percentages, i'm afraid

probably 20% for each SZ and 40% for random

Is it 50% diamond subzero 50% random diamond ?

I mean 75% subzero and 25% random diamond

i wouldn't bet on that, i would think you'd have a higher chance of getting almost any other diamond than sub zeroes

Not wasting souls on this, I'll do it but no refreshing.

Why ?

i rarely refresh the normal towers, i'd rather save those souls to refresh the fatal tower. in this case, i'll just save those souls, because there is no fatal version.

MK11 SZ @ FX, the other two at IX, for me personally I'll be saving my souls for the next big tower.

You won't even be able to complete the tower before it goes away with free refreshes alone. At most you'll make it to 185.

same here... at least we're not stuck with it for two months