Honorable Mentions Leonardo's Technique Kitsune's Technique Leonardo, Sewer Samurai April, Reporter of the World Krang, Master Mind Rat King, Verminister Super Shredder Casey Jones, Vigilante Leatherhead, Swamp Stalker Michelangelo, Mutant BFF
The variety also means niche strategies always exist for creative brewers
Therefore, if you are considering combo, my recommendation is to either have a combo that slays everyone quickly or add a few combo cards to decks that already exist, and if possible, to have those combo cards not look shockingly out of place
One side is cheap to allow you to cast it early, and the second side is six mana to give you a big spell to cast later in the game
However, thats all just speculation until we get some kind of announcement