Merfolk Skydiver — ruling 1

If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.

Merfolk Skydiver — ruling 2

To proliferate, you can choose any permanent that has a counter, including ones controlled by opponents. You can choose any player who has a counter, including opponents. You can't choose cards in any zone other than the battlefield, even if they have counters on them.

Merfolk Skydiver — ruling 3

You don't have to choose every permanent or player that has a counter, only the ones you want to add another counter to. Since "any number" includes zero, you don't have to choose any permanents at all, and you don't have to choose any players at all.

Merfolk Skydiver — ruling 4

If a permanent ever has both +1/+1 counters and -1/-1 counters on it at the same time, they're removed in pairs as a state-based action so that the permanent has only one of those kinds of counters on it.

Merfolk Skydiver — ruling 5

An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.

Merfolk Skydiver — ruling 6

Players can respond to a spell or ability whose effect includes proliferating. Once that spell or ability starts to resolve, however, and its controller chooses which permanents and players will get new counters, it's too late for anyone to respond.

Merfolk Skydiver — ruling 7

You may choose Merfolk Skydiver as the target of its own ability.

Merfolk Skydiver : règles, fonctionnement et interactions (MTG)

Merfolk Skydiver is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Flying When this creature enters, put a +1/+1 counter on target creature you control. : Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Complete guide

Merfolk Skydiver is a versatile utility creature that serves as both a source of growth and a late-game mana sink. It provides immediate value upon entering the battlefield and offers a repeatable way to bolster your entire board through the proliferate mechanic.

Taking Flight with Counters

When Merfolk Skydiver enters the battlefield, its triggered ability allows you to place a +1/+1 counter on target creature you control. This can be any creature you currently have on the field, including the Skydiver itself. This immediate boost makes it a relevant threat the moment it hits the table, while its flying ability ensures it can often peck over grounded blockers.

How Proliferate Resolves

The activated ability of Merfolk Skydiver allows you to pay {3}{G}{U} to proliferate. When this ability resolves, you choose any number of permanents and/or players that currently have counters. For each chosen permanent or player, you add another counter of each kind already there. Note that once the ability begins to resolve and you start choosing targets, no player can cast spells or activate abilities to remove those targets; the action happens all at once.

Important Interactions

Proliferate is all-or-nothing for the chosen object. If a permanent has multiple types of counters (like a +1/+1 counter and a flying counter), choosing it means it gets one more of each. However, keep in mind that +1/+1 and -1/-1 counters cancel each other out as a state-based action. If you proliferate a creature that has both, they may have already removed each other before you get the chance to add more. Additionally, you can only proliferate permanents on the battlefield—you cannot add counters to cards in exile or your graveyard.

Strategic Timing

Because Merfolk Skydiver's proliferate ability is an activated ability, it can be used at instant speed. This is best used at the end of an opponent's turn to utilize leftover mana, or during combat to suddenly grow your creatures larger than the opponent's blockers. Since it requires a significant mana investment, it is most effective once your mana base is established.

Interaction examples

The Self-Sufficient Skydiver

You cast Merfolk Skydiver for {G}{U}. When it enters the battlefield, its trigger targets itself. You place a +1/+1 counter on Merfolk Skydiver, making it a 2/2 flier. Later, you pay {3}{G}{U} to activate its ability. You choose Merfolk Skydiver, adding a second +1/+1 counter to it.

Ramping into Growth

Llanowar Elves

You have Llanowar Elves on the battlefield. You cast Merfolk Skydiver and choose to put its +1/+1 counter on the Llanowar Elves. Now, you have a 2/2 Elf that can tap for mana. During your next turn, you use the mana from Llanowar Elves to help pay for the Skydiver's {3}{G}{U} cost, proliferating to put another +1/+1 counter on the Elves and the Skydiver.

Sky-High Support

Birds of Paradise

With Birds of Paradise in play, you cast Merfolk Skydiver. You target Birds of Paradise with the entry trigger. The Birds of Paradise is now a 1/2 flier. In a later turn, you activate Merfolk Skydiver's proliferate ability. You choose both the Birds of Paradise and the Merfolk Skydiver (assuming it has a counter). Both creatures receive an additional +1/+1 counter, increasing your aerial pressure.

Guide written with AI from the official text and rulings. Official English text prevails.

How it works : Merfolk Skydiver

Original English text — Wizards of the Coast / Scryfall

#1February 4, 2023· Wizards of the Coast
If a player or permanent has more than one kind of counter on it, and you choose for it to get additional counters, it must get one of each kind of counter it already has. You can't have it get just one kind of counter it already has and not the others.
No other card is named in this ruling.
#2February 4, 2023· Wizards of the Coast
To proliferate, you can choose any permanent that has a counter, including ones controlled by opponents. You can choose any player who has a counter, including opponents. You can't choose cards in any zone other than the battlefield, even if they have counters on them.
No other card is named in this ruling.
#3February 4, 2023· Wizards of the Coast
You don't have to choose every permanent or player that has a counter, only the ones you want to add another counter to. Since "any number" includes zero, you don't have to choose any permanents at all, and you don't have to choose any players at all.
No other card is named in this ruling.
#4February 4, 2023· Wizards of the Coast
If a permanent ever has both +1/+1 counters and -1/-1 counters on it at the same time, they're removed in pairs as a state-based action so that the permanent has only one of those kinds of counters on it.
No other card is named in this ruling.
#5February 4, 2023· Wizards of the Coast
An ability that triggers "Whenever you proliferate" triggers even if you chose no permanents or players while doing so.
No other card is named in this ruling.
#6February 4, 2023· Wizards of the Coast
Players can respond to a spell or ability whose effect includes proliferating. Once that spell or ability starts to resolve, however, and its controller chooses which permanents and players will get new counters, it's too late for anyone to respond.
No other card is named in this ruling.
#7May 3, 2019· Wizards of the Coast
You may choose Merfolk Skydiver as the target of its own ability.
No other card is named in this ruling.