Thor (New Year)
As noted, it grants an excellent 30-40% Skill Boost to any Attack Skill.
However, it's a bit of a double-edged sword as it also self-inflicts Confusion on you.
Pretty good sub if you can work around the Confusion effect. Otherwise, be wary of using it.
However, the real draw of using Thor as a Sub is in conjunction with the other Subs from his Event:
- → Banquet Tassel: When Main Card's Skill Activates, (20/25/33%) Chance to prevent linking with Enhance Cards. When subbed alongside Thor (New Years) on the same card, chance increases to (60/80/100%)
- → Karaoke Machine: Grants (10-30%/15-35%/15-45%) Skill Boost and rare chance to activate Deca Shout. When subbed alongside Thor (New Years) on the same card, grants (20-30%/25-35%/35-45%) Skill Boost.
When Subbed alongside an SSS Banquet Tassel, Thor allows a card to not link with Enhance Cards. Especially notable in that you only need two cards to do it, allowing you to add an additional Sub of your choosing. This can be very useful for cards that don't directly benefit from additional Skill Boosts such as certain Sustain or Shield cards.