The mechanic
The Oasis Revenant is an armored undead naga with a large health pool. She never cloaks herself, so she is always a valid target, but she does not fight fair.
At 75, 50, and 25 percent health she sheds 2 mirage copies of herself, 6 across the fight. Each mirage carries the ghost's trick: the first time a mirage takes a hit it shimmers untargetable for 2.5 seconds before reappearing, which can waste a burst of tower fire.
When the revenant finally dies she does not go quietly: 5 fast marsh wisps burst out of her and scatter toward your base.
How teams beat it
Keep damage-over-time effects like poison rolling, since they tick through the mirages' cloak while direct fire gets wasted on the vanish. Have area damage ready for the death burst of marsh wisps so the last of her cannot slip past.
Like every boss, it fights inside the showdown rules: kill it and it respawns about twenty percent stronger on the rival's lane, let it leak and it crosses unescalated. The full showdown rules are in How a match works.
