This is where everyone's favorite part of the rules kicks in - layers!
The way layers work is that the game defines specific groups of conditions that change the aspects of a card. The lower the number, the earlier it applies. We're looking exclusively at layer 7 here, which deals with power and toughness and is split into 5 more layers itself.
The layers apply in the following order: 1. Define P/T 2. Set P/T 3. Modify P/T without setting it 4. Counters (e.g. +1/+1) 5. P/T switching
So let's look at the situation you have. With the Turtleshell Changeling and Plated Sliver on the field, the changeling will become a 1/5. If you use its ability, it becomes a 5/1. It doesn't gain any extra from the Sliver because it already has. This is because of rule 613.5, which reads:
If an effect should be applied in different layers and/or sublayers, the parts of the effect each apply in their appropriate ones. If an effect starts to apply in one layer and/or sublayer, it will continue to be applied to the same set of objects in each other applicable layer and/or sublayer, even if the ability generating the effect is removed during this process.
This also explains why the Changeling doesn't become a 4/2 when it switches its P/T.
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acbooster says... Accepted answer #1
No it would not.
This is where everyone's favorite part of the rules kicks in - layers!
The way layers work is that the game defines specific groups of conditions that change the aspects of a card. The lower the number, the earlier it applies. We're looking exclusively at layer 7 here, which deals with power and toughness and is split into 5 more layers itself.
The layers apply in the following order:
1. Define P/T
2. Set P/T
3. Modify P/T without setting it
4. Counters (e.g. +1/+1)
5. P/T switching
So let's look at the situation you have. With the Turtleshell Changeling and Plated Sliver on the field, the changeling will become a 1/5. If you use its ability, it becomes a 5/1. It doesn't gain any extra from the Sliver because it already has. This is because of rule 613.5, which reads:
If an effect should be applied in different layers and/or sublayers, the parts of the effect each apply in their appropriate ones. If an effect starts to apply in one layer and/or sublayer, it will continue to be applied to the same set of objects in each other applicable layer and/or sublayer, even if the ability generating the effect is removed during this process.
This also explains why the Changeling doesn't become a 4/2 when it switches its P/T.
September 30, 2017 9:08 a.m.