Illuminor Szeras does not have summoning sickness.
Steps
Activate Illuminor Szeras by tapping it and sacrificing Threefold Thunderhulk, adding seven ({B} magic symbol) .
Activate Reito Lantern by paying ({3} magic symbol) , putting Threefold Thunderhulk on the bottom of your library.
Activate Grenzo by paying ({2} magic symbol) , putting Threefold Thunderhulk from the bottom of your library into your graveyard, then putting it onto the battlefield.
When Threefold Thunderhulk enters the battlefield, it triggers, creating three 1/1 Gnome artifact creature tokens.
Activate Clock of Omens by tapping Threefold Thunderhulk and a Gnome token, untapping Illuminor Szeras.