You gain Soul Thread when you watch a new H-scene (for the first time!) or you can give gifts to companions. Skills are available from the start (there is one for each companion for now), to use them you need to slap their asses til it's red. If requirements are meet, she will use her skill.
If you have difficulties to pass shards, use Default Thong + vibro-toy. Pick Rest Shards and talk to Rose.
And yeah, we'll improve the battle system and add tutorials in the future, so players can easily navigate the game.
Thank you for playing!