Boundless gives the Medicinal Specter a duration increases from 18 to 28 seconds and radius from 12.5 to 17.6
Combined with Healing booster it gives 31 hp and 6.25% life regen per second, which is basically 200 hp at that stage of the game
The healing will carry every team fight if placed correctly, try to throw it in the middle of the team fight
The healing ring will be the area where you will place your turrets and move around while fighting
Escalating exposure is great for objectives but after the nerfs, on average (after game), it would boost your spirit damage by 12% upon spending 6.2k which is not worth unless it is the last item.