Selvala does not have summoning sickness and has at least one +1/+1 counter on it.
Steps
Activate
Selvala by tapping it, causing each player to reveal the top card of their library, then causing you to add ({G} magic symbol) and gain 1 life for each nonland card revealed this way, then causing each player to draw a card.
Activate
Selvala using
Pili-Pala's ability by paying ({2} magic symbol) and untapping it, adding one mana of any color.
Repeat.
Notes
Additional mana may be needed to start the combo depending on how many nonland cards are revealed. It is also possible that each iteration may not cover its own mana cost, and therefore it is recommended to have additional mana available in case this happens and you have no extra mana from previous iterations.