Add in the number of useful enchantments which can easily be cycled (including Cast Out, Shark Typhoon, and Decree of Silence), and you can appreciate the kind of power Replenish unlocks
If they run type-specific techs, then have a Greens in hand to be able to counter them, and attempt to have sufficient healing to force them to attack three times to take a knockout
In battle, Reshiram obeys Ns commands unwaveringly, demonstrating its trust in the Hero of Truth
He makes for a solid mono-white equipment commander, though you're more likely to see him in the 99
Flowering of the White Tree puts a tax on targeting your various legendary ring bearers and combo pieces, while simultaneously turning them into bigger threats and doubling your creature token size