When Ojer Kaslem dies, it triggers, returning itself from your graveyard to the battlefield as Temple of Cultivation.
When Temple of Cultivation enters the battlefield, Tiller Engine and Nissa trigger.
Resolve the Tiller Engine trigger, untapping Temple of Cultivation.
Resolve the Nissa trigger, adding ({G} magic symbol) .
Activate Temple of Cultivation's second ability by paying ({2} magic symbol) ({G} magic symbol) and tapping it, transforming Temple of Cultivation into Ojer Kaslem.