How is self-mitigated damage calculated?

Recently there was a change in the end game stats on the client, and one of the new stats show self-mitigated damage. While playing Jarvan IV, I managed to rack up ~40,000 in self-mitigated damage, which kind of makes sense as I use shield a lot and patch 7.9 states

Damage Mitigated on Self (how much damage you reduced or blocked on yourself through your abilities and shields)

However, the Ezreal in my game had ~7,000 self mitigated damage and he has no shields or damage reduction abilities. So how exactly is self-mitigated damage calculated?

I did a bit of research and apparently the stat shows all incoming damage that didn't directly affect your health bar.

This means basically every form of damage mitigation counts. (Blinds do not since they are a form of CC)

Some people on reddit are also complaining about shields from supports not counting towards the support's mitigated damage, but the target's.

For your example about Ezreal having 7000 damage mitigated on himself: Depending on the support he had, shields (Janna E,Morgana E,Bloodthirster) contribute to this stat but also items (Kight's Vow, Phantom Dancer) and spells (Exhaust, Urgot Passive).

However most of this mitigation will almost always come from resistances. Keep in mind that even a squishy marksman like Ezreal has at least 30-40 MR and 30-80 Armor. In addition to that most people run Armor and MR runes which results in quite a bit of mitigation, especially against bruisers or champions that haven't built any resistance penetration yet.

There are still three scenarios I'm not entirely sure about how they work: Stasis, Invulnerablity and Invincibilty.
DoT spells continue to tick if someone enters stasis, Tryndamere's ultimate simply doesn't let you die and Kayle's ultimate renders you completely immune to damage. I'll test these things and update the answer accordingly.