Finja will probably make the deck better overall but has fair less use in other decks.
Craft finja if you plan on playing this deck for awhile. Craft lich king if youre looking for long term playability and further use in other decks.
Personally Id go with The Lich King.

This deck is super fun and really effective.

I’ve found its effective to always keep 1 part of a big evolve turn, for example I keep thrall in my opening hand, or a single dopplegangster / evolve. Especially versus decks like Druid or the Mirror its really important to hit that turn 5/6 big evolve turn. Most of the time if you turn 5/6 dopple gangster evolve and then drop another evolve / deathseer the opponent will just concede straight up.

Against aggro, mulligan hard for flametongue / primalfin totem. Currently 20 – 6 with this deck from Rank 18 and im climbing far faster then with the other decks ive tried this meta like Highlander priest and Jade Druid.