Evoker mode was a stretch goal for the Patreon for a long time, and people have been asking for it since before that goal had even been met, and it has always been lower priority than story mode. It still has a few prerequisites (and higher priority items) before we get to it - the companion system we're working on now is going to be used by the Evoker for their demon pacts, and the generic battle animations we're filling out for Hiro are going to have equivalent Evoker ones (so that when Evoker is playable, it'll have plenty of content). We've been working on tooling (the encounter editor, primarily) and the finalizations of systems (AI, animations, and now the world map) before we complete story mode so that we we can be as efficient as possible while working on it and not necessitate expensive rework and retrofit, and Evoker will be next up after story mode is playable start to finish, which dovetails nicely with the non-erotic work that Alis is planning to do by then: right now she's in the middle of finishing up the backgrounds for encounters and towns, including the new towns, then she'll be finalizing the world map graphics and then completing the remaining UIs, at which point the generic Hiro animations will be done. Evoker mode will be the last thing added in Beta before we enter Pre-Release, which will be total feature lockout and just content generation and cleanup/polish.
tl;dr - once story mode is fully playable, Evoker mode is the next thing we're working on, and you'll be seeing more Evoker art/animations before then.