Soulblade Corrupter — ruling 1

Soulblade Corrupter's last ability won't trigger if a creature attacks a planeswalker.

Soulblade Corrupter — ruling 2

Soulblade Corrupter's last ability won't trigger if a creature without any +1/+1 counters on it attacks and receives a +1/+1 counter any time after attacking.

Soulblade Corrupter — ruling 3

Soulblade Corrupter's last ability will trigger if a creature an opponent controls with a +1/+1 counter on it attacks another player who's also your opponent.

Soulblade Corrupter — ruling 4

"Partner with [name]" represents two abilities. The first is a triggered ability: "When this permanent enters the battlefield, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle their library."

Soulblade Corrupter — ruling 5

Note that the target player searches their library (which may be affected by effects such as that of Stranglehold) and that the card they find is revealed, even though these words aren't included in the ability's reminder text.

Soulblade Corrupter — ruling 6

A nonlegendary creature can't be your commander, even if it has a "partner with" ability.

Soulblade Corrupter : règles, fonctionnement et interactions (MTG)

Soulblade Corrupter 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

Partner with Soulblade Renewer (When this creature enters, target player may put Soulblade Renewer into their hand from their library, then shuffle.) Deathtouch Whenever a creature with a +1/+1 counter on it attacks one of your opponents, that creature gains deathtouch until end of turn.

How it works : Soulblade Corrupter

Original English text — Wizards of the Coast / Scryfall

#1June 8, 2018· Wizards of the Coast
Soulblade Corrupter's last ability won't trigger if a creature attacks a planeswalker.
No other card is named in this ruling.
#2June 8, 2018· Wizards of the Coast
Soulblade Corrupter's last ability won't trigger if a creature without any +1/+1 counters on it attacks and receives a +1/+1 counter any time after attacking.
No other card is named in this ruling.
#3June 8, 2018· Wizards of the Coast
Soulblade Corrupter's last ability will trigger if a creature an opponent controls with a +1/+1 counter on it attacks another player who's also your opponent.
No other card is named in this ruling.
#4June 8, 2018· Wizards of the Coast
"Partner with [name]" represents two abilities. The first is a triggered ability: "When this permanent enters the battlefield, target player may search their library for a card named [name], reveal it, put it into their hand, then shuffle their library."
No other card is named in this ruling.
#5June 8, 2018· Wizards of the Coast
Note that the target player searches their library (which may be affected by effects such as that of Stranglehold) and that the card they find is revealed, even though these words aren't included in the ability's reminder text.
No other card is named in this ruling.
#6June 8, 2018· Wizards of the Coast
A nonlegendary creature can't be your commander, even if it has a "partner with" ability.
No other card is named in this ruling.

Interactions with other cards

These cards' text mentions Soulblade Corrupter.

Soulblade Renewer

Partner with Soulblade Corrupter (When this creature enters, target player may put Soulblade Corrupter into their hand from their library, then shuffle.) When this creature enters, support 2. (Put a +1/+1 counter on each of up to two other target creatures.)