It essentially lets you turn 3 mana into 4 ( plus tapping this land), but you have to target something thats able to attack, and actually get to attack
That player won't gain life, but any other effects of that spell or ability will happen
If Talon Gates of Madara isn't still in your hand as that ability resolves, nothing happens
You do need a lot of sorceries and instants to power the Disciple, and Dig Through Time has some tension with it, but I think this card is one of the more underrated ones in the set and sure to become a popular control option for the next eighteen months (though certainly not universally adopted, as there are some good Walkers and Dragons)
Thrumming Stone is a must-have addition to any of these relentless decks
You might be able to find this Pokmon TCG set for similar prices in some physical stores, but I doubt you'll do better online