Vantage

No — you always succeed at the action you choose; the risk comes from suffering penalties (losses of time, morale, or health) if you can’t place rolled challenge dice. (pages 7, 10)

Choose a numeric cost (or use the printed cost), reduce it by any paid skills, then roll challenge dice equal to the remaining cost (refresh all dice first only if the pool is short). Place rolled dice one at a time on open slots; any dice you can’t place are discarded to the penalty section and immediately cause the listed losses or setbacks. (pages 8–10)

No — if you previously performed a location action at that location you cannot perform another location action there (unless an action is marked “always available”), and you may not perform thematically contradictory actions if another player already changed the location. (page 7)

You may use boost powers at any time, even mid-action or during another player’s turn; boosts gained/paid on locations go to your character while boosts on other cards stay on those cards, and boost effects last until the end of your current turn. (page 11)

Yes — impact (⚡) slots can be used by any player (with the card owner’s permission) and grant the card owner any listed bonus when another player places a die there; you may also place dice on a co‑located player’s open slots with their permission. (page 9)

If you would gain a card you already have in your grid, instead place 1 boost on that card; if another player already has the card, the two players decide who keeps it — if it goes to you its dice are refreshed, boosts are lost, and you gain any “when placed” benefit, otherwise you gain 1 boost on your character. (page 10)