Today, there's a fantastic quick start guide available at magic.wizards.com/en/magic-gameplay, and it's easily a better introduction than the Portal rulebooks
Harsh Mercy isnt usually going to destroy the creatures youd want it to anyway, and Rukarumel definitely wants to be commanding a different deck and has little to no synergies with this one
This could just be semantics, but crystal counters would make perfect sense in a Final Fantasy setting
His ability to generate value and resources makes him a versatile and exciting commander to build around
The minus turning our creatures into tutors/extra value is exactly what you want vs the blue piles/loam decks
It can't be the target of Sorceress's Schemes, which reads in part "Return target instant or sorcery card from your graveyard or exiled card with flashback you own to your hand." When playing a card as an Adventure, use the alternative characteristics and ignore all of the card's normal characteristics