Jonathan Isaac
Despite having had three major knee surgeries in his career, Jonathan Isaac has had an excellent season so far and looks back to his dominant defensive ways. But the Magic are deep and Isaac only averages about 13.5 minutes per game, so they could look to move him for the right price.
Adding Isaac would give the Heat a dominant defensive frontline along with Butler and Adebayo. There was a time when both Isaac and Adebayo were considered for Defensive Player of the Year.
Offensively, Isaac is struggling with his 3-point shot this season (28.3%) but he's a career 33% 3-point shooter on small volume, so there could be room to improve. But, at 6-foot-10, Isaac could have an immediate impact as a lob threat from the dunker spot.
Miami isn’t a big team and needs to look at another body that can defend the likes of Joel Embiid and Kristaps Porzingis in the postseason. Issac would add much-needed size and another versatile defender to the roster.
Acquiring Isaac could be worth the risk, and since his contract next year is non-guaranteed, the Heat could always cut bait if things don't work out or if they need to save money against the cap. This would be a high-upside, all-in move for the Heat.