Like Kicker, its the same as it ever was, giving bonuses to creatures and spells when a land enters the battlefield
The second ability Delney has reads: If an ability of a creature you control with power 2 or less triggers, that ability triggers an additional time. That means literally any triggered ability - including enter the battlefield triggers, damage triggers and more - now gives you double value
In a dedicated dice rolling deck, this is gonna be nuts, but itll do some work in Spellslinger builds, regardless
Should this alternative not be to your fancy, Marauding Raptor and Knight of the Stampede are other cost-cutting options
But yes overall i totally see that staying alive with this kind of strategy is the primary goal and removal is super important
Blue-black uses its incremental advantage to eke out every small gain it can