If an effect states that Thousand Moons Infantry doesn't untap during your untap step, that effect won't apply during another player's untap step
BPhillipYork: Really solid for mana dorks, or decks convoking things, or decks full of creatures with tapping activated abilities, however activated abilities that are good, that don't cost mana, but require tapping, are fairly rare, so it's hard to see this paying off all that cohesively unless you want to do something like use Opposition
Others have more humble aims, like the Sleight of Mind plus circles of protection decks we all messed with in the 90s
A Brief History Built upon the groundwork laid by MTGs original creator, Richard Garfield, Battle cards are an evolution of the scrapped Structures mechanic
Again, I think that lets do the same thing, again, but more efficiently this time is a very white ability