Youre usually required to sacrifice creatures or wait for creatures to ETB first
Aatchik, Emerald Radian Altanak, the Thrice-Called Amzu, Swarm's Hunger Baxter, Fly in the Ointment Fumulus, the Infestation Grist, Voracious Larva Kathril, Aspect Warper Lord Dregg, Insect Invader Mazirek, Kraul Death Priest Stockman, Mad Fly-entist Swarm, Being of Bees Szarel, Genesis Shepherd The Wise Mothman Thriss, Nantuko Primus Vishgraz, the Doomhive Vrestin, Menoptra Leader Wekhdu, Midnight Hunter Xira Arien Xira, the Golden Sting Zabaz, the Glimmerwasp Zask, Skittering Swarmlord
As long as many of your permanents are mana value 3 or less, you can always have something to return to the battlefield when Sun Titan attacks or ETBs
These are the most valuable poster cards (not counting the serialized cards
For one, a ton of green tutors, Chord of Calling, Finale of Devastation, etc., are on the watch list