The timings of the things happening on cards are a little difficult sometimes.
+ Cards and + Victory Tokens (from the Prosperity Expansion) happen immediately.
+ Actions are accounted immediately, but not spent immediately. GendoIkari explained how it works very well, so i'll not repeat him here.
+ Buys and + Coins are accounted the same way Actions are. The difference is that you may spend them in your buy phase, which comes after your action phase.
All other texts are resolved immediately, unless they are specifically referring to any other moment.
Text under a stroke always has those moments specified, so it never happens immediately when you play a card. Cards with those strokes are:
- Reactions, which only happen if the card is NOT in play and are on blue cards (like Moat)
- "While this is in play"-conditions, which only happen if, additionally to the condition happening, the card IS in play (like Herbalist).
- "When you gain this", "When you buy this" (Hinterland Expansion) and "When you trash this" (Dark Ages Expansion), which simply happen if you, well, gain, buy, or trash the card, respectively.