Both Ruin Raider and Fathom Fleet Captain make blocking necessary for an opponent, forcing them into situations where they might rather not make a tradeor you can surprise them with removal of your own
Read More: Modern Horizons 2 Cards Caught On Camera Inside Forgotten Realms Boos ters Ebondeath, Dracolich Carrying on the Mythic cycle of Dragons is Ebondeath, Dracolich which offers a sacrifice outlet for Commander
Theres nothing that says one way or the other, as far as I can tell
Go ahead and run a few ways to nuke graveyards, like Soul-Guide LanternSoul-Guide Lantern and Rest in PeaceRest in Peace, to help you out against graveyard decks in case you have to deploy your commander before your big, life-gaining, game-winning turn
you cannot Special Summon monsters for the rest of this turn, except Fusion Monsters, also send 1 "Elemental HERO" monster from your Deck to the GY, except "Elemental HERO Blazeman", and if you do, this card's Attribute and ATK/DEF become the same as the monster sent to the GY, until the end of this turn