Facilier can be used to immediately challenge again, making for quick recoveries from banishment that keep an opponent on the defensive
Sink into Stupor / Soporific Springs Disruption and mana consistency come together in Sink into Stupor, offering a bounce effect on one side and a blue-producing land on the other
Also doing heavy lifting with Kenrith: Biomancers Familiar is another Training Grounds that can actually attack too, but being a creature makes it much more vulnerable in a game of Commander than an enchantment which is why Training Grounds gets the #1 spot
They have a strong sense of deck identity
However, with the basic Swamp requirement, your mana base needs to be almost exclusively basic Swamps and Cabal Stronghold to really make Cabal Stronghold function, which probably isn't worth the cost in Modern, where splashing a second color and playing utility lands likely give you more power than maybe making extra mana with Cabal Stronghold, and it might not even be worth the cost in Standard