Unctus's Retrofitter

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.

A player with ten or more poison counters loses the game. This is a state-based action and doesn't use the stack. In other words, it happens immediately and players can't respond to it, just like a player losing the game due to having 0 or less life.

If a creature with toxic deals combat damage to a creature or planeswalker, or if it deals noncombat damage, toxic has no effect and no player gets poison counters.