Traditionally the star is black, but a card with a star of an alternate color such as white or gold means it's ultra rare
If you find its mana cost a bit too much, then opt for the Plot mechanic, which does delay the casting but also reduces the cost by a single green mana
Please purchase until the end of the event
It does have a steep cost to using it, though, requiring you to put two of the energies attached to Giratina VSTAR into your Lost Zone, but if you can close a game with an attack or two, it will be well worth it
add 1 "Time Stream" from your Deck to your hand
The unveiling of new set mechanics is always my favorite part of spoiler season, since their quality has a huge impact on how we perceive that expansion