Ghosting is a defensive technique: zero out the troops in your keep (and Rally Spot) so an attack kills almost no troops (walls and traps still take damage). Use it when you cannot bubble: immediately after entering the Battle of Constantinople/Gaugamela, or when staying a long time on an enemy server in SvS (you cannot put a shield on an enemy server). METHOD: rally surrounding cities/buildings/boss monsters for 60 minutes to drop keep troops to 0; turn OFF subcity 'automatic fight for other cities' (else subcity troops die); spend resources or bank them in the Alliance Warehouse, keeping on-hand below the warehouse-protected amount. In SvS you MUST resign the defense general before ghosting or he DIES when attacked (true since 10/3/2021); in BoG/BoC the defense general does NOT die, so you may leave him on. RALLY (not a plain march) because cancelling a rally returns troops to the keep INSTANTLY so you can defend/attack/teleport; you cannot teleport while marching or during a rally (cancel all rallies first). TARGET CHOICE: rally a BOSS MONSTER (costs stamina) rather than a city - rallying a city/temple/throne DEACTIVATES your shield and alerts the enemy to your exact troop count/type, while rallying a boss keeps the shield UP and hides your strength. If you must use a city (e.g. BoC has no bosses), pick a NON-allied city (the target's allies would otherwise see your formation). IF ATTACKED while ghosting: walls still lose HP and at 0 HP (or ~10 hits; 3 hits in BoG/BoC) you are 'sent flying' to a random spot and ALL rallied troops return to the keep - decide instantly to re-ghost or teleport (some enemies zero your HP, Arrest-Warrant-search you, and chase the returned troops). If the boss/city you rallied disappears, the ghost stays intact. PREP: bookmark ghost targets (bosses and non-allied cities) in advance; you cannot ghost to targets on your own server while on an enemy server. A scout of a ghosted city reports 0 troops. COUNTERATTACK: if you think you can win, cancel the ghost the moment you are attacked and win on defense (advanced: switch subcity auto-fight ON to add mayor debuffs). BAIT ('dare to leave some'): leave a few troops or one troop type to look weak, then recall the rest the instant the enemy commits.
Original research source: Evony Guide Wiki