In Commander, thats most likely to involve a Souls Attendant or two and a Serra Ascendant, but dont discount grabbing Stoneforge Mystic or Sram, Senior Edificer plus Fervent Champion or Ragavan
You Make the Discard You're playing a game of Kaladesh - Aether Revolt Limited
for example, if you have drawn multiple copies of Kolvori and want to get use out of the extra copy, or if you have nothing to do on Turn 2 and developing a slightly-below-rate mana rock is better than doing nothing
C Common Warning Point X TRAP When a monster(s) is Summoned: This turn, that face-up monster(s) cannot attack, its effects are negated, also it cannot be used as material for a Fusion, Synchro, Xyz, or Link Summon
The number one issue Ive had when trying to track down an art credit for Cube includes has been from people using Google Images
the last one I recall reading was an UG one by J-Wittz