Instead is an important game term in the Trading Card Game.
Some abilities say that if one thing (a game event) would happen, another thing happens instead.
For these abilities, the original event never occurs. It's replaced by an entirely new event that happens when the first event would have happened. For example, if your Aqua Commando would be banished, it returns to your hand and your opponent can't draw a card with the ability of their Black Feather of Shadow Abyss.
If this creature would be banished, return it to your hand instead.
If this creature would be banished, put it into your shield zone face down as a new shield instead.
If this creature would be banished, put it into your mana zone instead.
When a replacement effect applies, the original event doesn’t happen at all. So, if loses a battle (or would be banished some other way), it instead goes directly to your mana zone. It’s never put into your discard pile. An ability that triggers “whenever one of your creatures is banished” wouldn’t trigger, because Red-Eye Scorpion wasn’t banished. However, an ability that triggers “whenever a card is put into your mana zone” would trigger.
“Chains” of replacement effects
Replacement effects can work together in some situations. After applying a replacement effect, check the new event to see if any other replacement effects may apply to the new event. For example, consider Red-Eye Scorpion and another creature with an ability that says “If one of your creatures would be put from the battle zone into your mana zone, put that creature on top of your deck instead.” If Red-Eye Scorpion would be banished, that event is replaced with Red-Eye Scorpion being put into your mana zone. However, the other ability now applies, replacing Red-Eye Scorpion being put into your mana zone with it being put on top of your deck. The end result is that Red-Eye Scorpion is put on top of your deck.
“Loops” of replacement effects
Each replacement effect can apply only once to any event, including new events that replaced it.For example, consider a creature with an ability that says “If you would draw a card, draw 2 cards instead.” If you would draw a card, that event is replaced with you drawing 2 cards. That ability can’t affect that event again and cause you to draw 4 cards, then 8, and so on.
A replacement effect is optional if it includes “you may.” If an optional replacement effect could apply but you choose not to use it, it won’t try to apply to that same event.
If a replacement effect replaces an event happening to a creature with the same event happening to another creature, the new creature must be one that isn’t already being affected by the original event. For example, says “Each time one of your Shadow Champions would be banished, you may banish one of your other creatures instead.” If you have two Shadow Champions that would be banished at the same time, you can pick any other creature to be banished, but you couldn’t pick the same creature to be banished instead of both Shadow Champions. You also couldn’t just choose the second Shadow Champion to be banished instead of the first, resulting in the second Shadow Champion being banished twice. Multiple replacement effects If more than one replacement effect could apply to the same event, the player whose turn it is chooses one of his or her effects to apply. If the player whose turn it is doesn’t have any replacement effects, the other player chooses one of his or her effects to apply. Then, look at the new event to determine if any other replacement effects (starting with those belonging to the player whose turn it is) apply. Keep applying replacement effects to new events in this way until no more apply.