Insidious Roots fits into decks like Teval, the Balanced Scale, The Necrobloom basically anything that uses the graveyard for value
Heliod, the Radiant Dawn / Heliod, the Warped Eclipse Heliod, the Radiant Dawn is just an oversized Auramancer, but transform this baddie and you get Heliod, the Warped Eclipse, a Phyrexian god that converts opponents card draw into cost reduction for your spells
I think early pack two is a good point to decide what to commit to, but again, it's way too early to delineate a successful strategy, so take this with a pinch of salt
the cards' desire to win at all costs were what inflicted the damage to his heart (in the original, Judai also mentions a wide variety of reasons why the cards might do so)
Legendary artifacts and equipment from Magics past are now eligible commanders, opening up hundreds of new deck building possibilities