613.3a Layer 7a: Effects from characteristic-defining abilities that define power and/or toughness are applied. See rule 604.3.
613.3b Layer 7b: Effects that set power and/or toughness to a specific number or value are applied. Effects that refer to the base power and/or toughness of a creature apply in this layer.
613.3c Layer 7c: Effects that modify power and/or toughness (but don't set power and/or toughness to a specific number or value) are applied.
613.3d Layer 7d: Power and/or toughness changes from counters are applied. See rule 121, "Counters."
613.3e Layer 7e: Effects that switch a creature's power and toughness are applied. Such effects take the value of power and apply it to the creature's toughness, and take the value of toughness and apply it to the creature's power.
Builder's blessing applies in layer 7c, and the p/t switch effect applies later in layer 7e. So you would apply builder's blessing first, then the p/t switch, resulting in a 5/1. If you discarded another card, all it does is switch back: its original p/t is still 1/3, and layer 7c still makes it a 1/5 off the bat. Switching it merely swaps the two back and forth, it will never grow larger like you seem to imply.
When I discard a card to swap the power and toughness is Aquamoeba a 3/3, 5/3, 5/1, or what?
If it's like a 5/3 and I discard another card does it become a 3/7 and another discard becomes 9/5, etc?
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Builder's blessing applies in layer 7c, and the p/t switch effect applies later in layer 7e. So you would apply builder's blessing first, then the p/t switch, resulting in a 5/1. If you discarded another card, all it does is switch back: its original p/t is still 1/3, and layer 7c still makes it a 1/5 off the bat. Switching it merely swaps the two back and forth, it will never grow larger like you seem to imply.
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