Some examples of themes could be: Mechanic-Based Builds - All cards in the cube synergize with a particular mechanic, such as landfall flashback Tribal Themes - Built around tribes for each color (Zombies, Merfolk, Goblins, Eldrazi, etc.) Set Themes - A cube built using cards from particular sets and blocks in MTG (Innistrad, Kamigawa, Ravnica) Format-Themed Builds - For example, a Modern cube would feature only cards legal in Modern +1/+1 Counters Or Artifact Themes - Where most cards (regardless of color) synergize with the same thing Mono-Colored Themes - A cube built with a single color, using all the styles it offers There are no wrong answers here
5 @DoubleCure: "from week 5 trials and onwards" That's still one week away
Fateful Absence does leave behind a clue that your opponent can sacrifice to draw an additional card
For the Liliana's Reaver I'd run Mindleech Ghoul as it's faster to get cards out of all my opponents hands
In dedicated Sacrifice decks, it's not uncommon for Mazirek to become giant as soon as it hits the field if you have a sacrifice outlet and permanents to sacrifice