This was suppose to be an easy game, but it seems not… Here is a guide from @LANshark
Try using several simple actions that cannot be denied in a string.
It should proably all be done by one merc so it does not take to long and/or switching mercs which resets abilities (hbs).
If you can get a few people doing this it should be easy.
Ex.
vassili- throw hbs, switch to machine pistol, run to hbs, trow hbs when old hbs runs out (position moves to look for phantom or at obj), shoots phantom if he appears.
rhino- switch to minigun, wait for vassili to throw hbs, run to hbs detection area, shoot phantom if he appears.
proxy- switch to mines, place mines at chokepoints/around corners (use for damage/ early warning), go to hbs detection area, only leaving when new mines must be places, shoot phanom if he appears. Mines can also prevent Phantom from fleeing, leaving his cloak on for an extra turn.
Redeye- stay with vassili, use sight to look for vassili, cover proxy when she leaves to reset mines (remain in line of sight of main group), shoot phantom if he appears. Redeye can also independently see Phantom for one turn, and his smoke can stop allies from being killed.
These are examples, your class is free range, unless you state your class. If it is a DB class, you can play as him.
if we cannot kill him, we sit by the objective to prevent plant and win off of time, keep in mind that Phantom killing everyone will automatically stop the clock. The OBJ needs to have one person guarding for 5 turns.