For spells and traps, the triplicate set of Ojama Trio, Just Desserts, and Secret Barrel are almost always played in full numbers
Pair this ability with shift 5, two other cheaper Dr
With the singleton decks required by the Commander format, they'll eventually have to get rid of certain cards central to their strategies, leaving them unable to play how they want
When your "Welcome Labrynth" Normal Trap card resolves, you can make so it also destroys 1 card on the field: this effect doesn't activate and doesn't target, and it's simply added on resolution of any "Welcome Labrynth" Normal Traps activation, making it count as a Normal Trap effect being able to trigger all your effects
That leads to needing to ban things like High Tide, Strip Mine, Mishra's Factory, Goblin Grenade, Sinkhole, and Hymn to Tourach, among a few possible others