“Mirage Knight” cannot be Normal Summoned or Set, and cannot be Special Summoned EXCEPT by the effect of “Dark Flare Knight”. So “Mirage Knight” cannot be Special Summoned with “Monster Reborn”, etc., even if Special Summoned properly first.
“Mirage Knight” can be Special Summoned by “Dark Flare Knight”’s effect even if “Skill Drain” is active, because “Dark Flare Knight”’s effect activates in the Graveyard. However, “Mirage Knight”’s effects are negated by “Skill Drain”.
When a “Mirage Knight” that was involved in battle is flipped face-down, it is not removed during the End Phase.
When a “Mirage Knight” that was involved in battle is removed from play with “Interdimensional Matter Transporter” or “Dimensionhole”, it is not removed from play during the End Phase by its own effect.
Netrep Rulings:
“Mirage Knight” raises its ATK based on the original ATK of the monster involved in battle with it.
If “Mirage Knight” is involved in Damage Calculation, it will be removed from play at the end of the turn.
If “Mirage Knight” is involved in battle while “Skill Drain” is active, it will not receive its increase to ATK. If “Skill Drain” is activated after “Mirage Knight” has been involved in battle and remains active through the End Phase, “Mirage Knight” will not be removed from play.