The goal is to exploit something smaller and keep the 4/6 deathtoucher intact, but sacrificing Sidisi to itself and grabbing a mass reanimation effect is always a solid gameplan, too
The spear was a bust
There is a lot of countermagic in this cube (Mana Drain, Miscalculation, Memory Lapse, Remand, Daze, Counterspell, Three Steps Ahead, Spell Pierce, Mana Leak, Force of Negation, Force of Will, Cryptic Command, Tishana's Tidebinder, Force of Will, Subtlety, Mystic Confluence, No More Lies), so if you are a control player at heart, you can end up playing Blue/White with counters, sweepers, card selection and finishers like Teferi, Hero of Dominaria or Fractured Identity
Artifact - Book Color tag templates(None) Urza's Incubator As this artifact enters, choose a creature type
Which brings me to my next point
The indestructible ability is pretty sweet and will make Tyvar difficult to deal with