RCB lost six wickets for only 25 runs in the chase after a strong start, but Karthik and Swapnil counterpunched to complete the win.
Shamar Joseph, Andre Russell included for home team in the global event.
South Africa men will take on Sri Lanka in two Tests and Pakistan in an all-format tour.
Cummins bowled a superb 19th over followed by Bhuvneshwar successfully defending 12 in the final over.
Meanwhile, star Men in Green pacer Haris Rauf returned to the squad after missing the recently concluded New Zealand series due to a shoulder injury
The spinners combined for eight boundary-less overs that fetched them four wickets for just 33 runs.
Cricket Canada named their 15-member squad on Thursday for the upcoming T20 World Cup.
Afghanistan Cricket Board (ACB) on Tuesday announced the 15-player squad for the upcoming T20.
Steve Smith, Fraser McGurk left out as Australia names T20 World Cup 2024.
Marcus Stoinis once again rescued a win as Lucknow Super Giants emerged triumphant with a four-wicket win against Mumbai.
