2023-02-04 : Effects that modify a creature's power and/or toughness, such as the one created by Blazing Crescendo or a +1/+1 counter, will apply to the creature no matter when they started to take effect.

2023-02-04 : If Unctus's Retrofitter leaves the battlefield before its enters-the-battlefield ability resolves, that ability will have no effect. The target artifact won't become an artifact creature at all.

2023-02-04 : If the artifact was already a creature, its base power and toughness will become 4/4. This overwrites any previous effects that set its base power and/or toughness to specific values. Any power- or toughness-setting effects that start to apply after Unctus's Retrofitter's ability resolves will overwrite this effect.

2023-02-04 : The resulting artifact creature will be able to attack on your turn if it's been under your control continuously since the turn began. That is, it doesn't matter how long it's been a creature, just how long it's been on the battlefield.

2023-02-04 : The target artifact retains any types, subtypes, and supertypes it has.

2023-02-04 : Unctus's Retrofitter doesn't remove any abilities the target artifact has.