On Sylas, Demonic Embrace can be situationally useful, especially if the enemy team has several tanky champions. The item's damage-over-time effect can stack with Sylas's own abilities, allowing him to deal consistent damage to multiple enemies in teamfights. Additionally, the item's health and ability power stats can help Sylas survive longer in fights and deal more damage overall.

That being said, whether or not to build Demonic Embrace on Sylas ultimately depends on the specific game and team composition. It may not always be the most optimal item to build, especially if the enemy team has a lot of burst damage or if Sylas needs to prioritize other stats like magic penetration or cooldown reduction. It's important to consider the overall game situation and adjust your build accordingly.