You can't put more than one +1/+1 counter on any one target using the support action.
Soulblade Renewer
"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."
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.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Suzanne Helmigh
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
