To obtain the Celestriad, also known as the 1 MP Cost Relic, in Final Fantasy VI Pixel Remaster, you can follow these steps:

1. Location: The Celestriad can be found in the World of Ruin in the Dinosaur Forest, which is located to the north of The Veldt.

2. Method 1: Winning from Brachiosaur:
– Enter the Dinosaur Forest in the World of Ruin.
– Engage in battle with Brachiosaur.
– There is a chance of winning the Celestriad from Brachiosaur.

3. Method 2: Stealing from Galypdes:
– Find Galypdes in the Phoenix Cave.
– Engage in battle with Galypdes.
– Steal the Celestriad from Galypdes.

4. Method 3: Betting in the Coliseum:
– Visit the Coliseum in the World of Ruin.
– Bet a Soul of Thamasa to win the Celestriad.

By following these methods, you can acquire the Celestriad, which reduces the cost of all magical powers in the game to a mere 1 MP, making it a highly valuable relic for any party.