Archon of the Wild Rose's ability overwrites all previous effects that set the affected creatures' power and/or toughness to specific values. Other effects that set these characteristics to specific values that start to apply after Archon of the Wild Rose enters the battlefield will overwrite this effect.

Effects that modify a creature's power and/or toughness without setting it will apply to the affected creatures no matter when they started to take effect. The same is true for counters that change a creature's power and/or toughness.