Game Concepts
On top of powerful abilities, many cards also have keyword abilities that affect how they interact with other cards
For example, if a player sacrifices a 3/3 creature to cast Fling, and you copy it with Reverberate, the copy of Fling will also deal 3 damage to its target
Galadriel, Light of Valinor is limited to three triggers per turn, but if you can trigger one or two reliably, its already very good
I said before the tournament that if I was going and if I spent the time to prepare, I probably would have ended up making something along the same lines: Arceus alongside a toolbox of attackers that cover for weaknesses and threats
Underwater Tunnel // Slimy Aquarium This card seems to fit neatly into an Izzet Room archetype, and the Underwater Tunnel half, at just one mana, is especially critical for getting a Room on the board early