CC spells duration difference??

[Naki]

I am trying to block a unit from moving/attacking for several turns.
I am playing with Sanctuary (Irina), for some reason the spell duration looks as one number (4 for example) and when I cast it and look at the creature it has been cast on, it shows another number (3 for example).
Why does that happen? Thanks!

[Avonu]

It seems sometimes game count turn before unit action as first turn. At least it was before patches, I don't know how it is now (ex. Agony or "posion" effects hit target before it move - it same mechanism as in case of cyclops' ability).

[Naki]

It seems sometimes game count turn before unit action as first turn. At least it was before patches, I don't know how it is now (ex. Agony or "posion" effects hit target before it move - it same mechanism as in case of cyclops' ability).

I am not asking about spells that damage the creature. I am asking about Serenity, Blind, Petrify, Time Stasis/etc.

[Avonu]

It seems sometimes game count turn before unit action as first turn.

But to b honest I forgot about other possibility outside bugs - magic resistance. This stat could shorten spell duraction... maybe.

[Spin]

The spells show the effect for a unit with 0% magic resistance i think. This is why Spells like Time Stasis always say 3 turns but you rarely ever get a 3 turn Time Stasis on a creature.

[Mirez]

I think the tier of a unit might also matter. For example, serenity works longer on core creatures than champions.

[JypeFIN]

I think Magic Defence affects also to the spell duration. If a creature has high MD spell duration will be shorter.