Skyship Plunderer
Oracle Text
Flying
Whenever Skyship Plunderer deals combat damage to a player, for each kind of counter on target permanent or player, give that permanent or player another counter of that kind.
Card Rulings
2/9/2017 Skyship Plunderer’s triggered ability can target any permanent or player, regardless of which player was dealt combat damage.
2/9/2017 Skyship Plunderer’s triggered ability gives only one counter of each kind. It doesn’t double the number of each kind of counter. For example, if a creature has two +1/+1 counters and a charge counter on it, it gets one +1/+1 counter and one charge counter.
2/9/2017 To give a counter is to put a counter on a permanent or to have a player get a counter. Effects that interact with a player getting counters or counters being placed on permanents interact with Skyship Plunderer’s triggered ability.
I'm hoping there's some difference. I HATE the creation of keywords, immediately followed by pretending that keyword doesn't exist. That really pisses me off. Don't make me learn a keyword and then stop using it. I'm stilling pissed off about Fading/Vanishing. It's the exact same ability.
In this case:
Proliferate = Any number of permanents/players (not targeted, multiple), get an additional counter that was already there (singular).
This mechanic = A target permanent/player (targeted, singular), gets an additional counter of each counter that was already there (multiple).
Proliferate let you put more counters on everything.
This card puts extra counters on ONE TARGET.