It isn't once per turn and it doesn't have any restrictions
Now that extra caveat is out of the way, its time to talk about Palantir of Orthanc properly
The ability to give our fatties trample is nice, but theres also quite a few toolbox type creatures that can be extremely valuable to tutor for

Of course, fans who do not know this background cannot escape the perception that the card battle animation is a kind of box office check, so they hope for a sequel to be produced, which is forgettable and unlikely.[25] In the animation at the time, the cards used were sometimes banned or had different performance than the original, and even explanations of the situations that occur due to the activation and processing of specific cards were vague, and there were many supporting characters who were simply impressed by the monster's combat power or effects, so it may feel frustrating to those who know OCG.[26] There are opinions that it is not awkward if viewed as a simple boy battle, but unlike creative works, fans often have different perspectives over time, so criticism that it is childish or excessive is an element that cannot be resolved.[27] In other words, Konami can be seen as having decided that it is no longer possible to use the original theme as a means of promoting IP

GREAT GIFT FOR ANIME & TCG FANS: A fantastic choice for fans of the game card game genre, this one piece cards booster box makes a fun gift for birthdays, holidays, and special occasions
Special Pokemon Cards Collectors Love Modern Pokemon card formats and variations include several special card types that are highly collectible