The only issue, assuming you don't consider costing ten mana an issue, is that resolving four cascades in a row can get complicated, especially when individual cascades hit other cascade spells mid-resolution
As your first main phase begins (immediately after your draw step), you put another lore counter on each Saga you control
Blightbelly Rat also proliferates when it dies, adding yet another poison counter
With your Commander out, it can do both at once, resulting in legendary, game-winning blowouts
If you roll a die for any other reason (to simulate a coin flip, to choose pizza toppings, to create alternate timelines), that roll doesn't count
The first flies and can block a bunch