Backup confers only abilities that are actually printed below it. Any abilities that are gained by the permanent are ignored, including abilities gained due to a resolving spell or ability or copy effects.
Streetwise Negotiator
If a backup ability causes another creature to gain abilities, the creature with backup will still have those abilities.
Streetwise Negotiator’s ability doesn’t actually change any creature’s power. It changes only the amount of combat damage the creature assigns. All other rules and effects that check power or toughness use the real values, even if they cause damage “equal to a creature’s power” to be dealt. Notably, if Streetwise Negotiator (or the creature that gains its ability) fights, it uses its actual power to determine how much damage it deals.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Brent Hollowell
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
