Yes you can use it as a sacrifice for another creature. It doesn't necessarily need to be stronger. However, as you mentioned this card does now go into your cemetery and would add 100hp to your cemetery towards loosing the game. It is a fine balance of using a powerful creature they gave you with the cost of discarding cards. Or making that choice to add 100hp to your cemetery.
Yes you can use it as a sacrifice for another creature. It doesn't necessarily need to be stronger. However, as you mentioned this card does now go into your cemetery and would add 100hp to your cemetery towards loosing the game. It is a fine balance of using a powerful creature they gave you with the cost of discarding cards. Or making that choice to add 100hp to your cemetery.
-Tom
Ward Trading Card Company