The Obama team was way too smart to launch an operation to spy directly on Trump. Instead they saw an opportunity to do just that under the guise of investigating the Russian Election Interference allegations. As they sifted through the intel looking for dirt on Trump, they knew they had plausible deniability.
As usual, Obama bent the rules way past ethical and yet he may have still technically been on the legal side of things. Then he changed the laws to allow 16 government agencies to have access to their "accidentally" discovered intel, knowing that with that many eyes on it, it would be probably be leaked. They hoped that the results would be damaging to the incoming Trump Administration.
I believe that when all his devious plots are looked at all together, the IRS scandal, the Benghazi scandal, the spying on his enemies, etc., the Obama Admin was the most morally bankrupt administration in my lifetime, worse than even Nixon's. But, like a Mafia Don, he's probably untouchable. If anybody goes down, it'll just be foot soldiers like Susan Rice or Evelyn Farkas.