u/Cyanide-pills

So, I have the Viktor premade deck with innovator and the Fiora one coming soon. Im really new to card games and TCGs but have been having fun with Riftbound. I wanted to ask for help/advice with playing and winning on both decks. I do have some extra cards from booster packs but im not too sure if they're any good or have any synergies. Personally, I found that I seem to prefer/enjoy managing my runes, as in I like to get lots of them and have resources. My friend who I played with also noted the same, so if thats helps theres that. The Viktor deck also hasnt been changed at all.

Currently a paragon 756 Inferno IV and im tryna get some essences for a summoner necromancer build. Gonna ask since I cannot figure out, whats the best way to farm for legendary essences and gems aside from elder rift?(Ive run out of crests)