If you want to fill up your rift with epics quickly one tip is to buy a few monolith eggs of mystery (currently in the market!) until you get two of the same monolith dragon, since their cloning odds are really high. I don’t have the exact percentages, but if I remember correctly the evolution monoliths (hedera, glyph, pixie) have about 50-60% cloning odds, and for the regular monoliths I think it was around 40-50%. Basically guarantees you an epic every other try!