1: the power of immunity:this power to render something null.

for example, immunity to flames = no flame no matter how hot even if it was the sun or the burning nova would affect you.

2: the "balance change" done by the MC to the world when he changed the immunities to 100% reduction in effect is in fact a nerf

which is why he made a balance buff to compensate and made those people who got balance changed his race.

explaining the nerf:if you are immune then you take null dmg and effect 

however with 100% reduction in dmg and effect you could still fight someone who has some form of amplifying effect to counter you.

for example 100% reduction (which can be increased more by multipliers) is countered by 100% dmg + lets say a skill or effect that deals +0.5 dmg bonus.

3: the immunity using vague words such as "control from last chapter" could take the many meanings of the words

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for example: control = enslave or control = directing or control = sealing something to prevent something from happening, you control a water using pipes etc and so on.

we basically can have many types of controls and this new race is immune to such control which is why it is an over powered blessing

4:immune to aging, now what this means is not exactly that they won't age* but they are immune to aging effects

for example, you could root and decay by aging which this new race won't, it doesn't mean that they won't grow but they simply wont be affected by the aging*(decay)

5:the people in the examples shown in the chapter where they broke free from the "control" placed on them all had some form of

immunity one way or an other, being ageless or immune to darkness or even immune to fire or light etc and even immune to farting would count as an immunity race now.