Info taken from FAQs in file area and various forum threads, consolidated into a Wiki page so that people can more easily find all the info in one place and update it.
List of game FAQs
Remember that the starting player may not play a God card in his first game turn after the initial map creation. It's easy to overlook this rule!
Q: Can I play a card before declaring my turn option?
A: No. (Rio Grande)
Q: If during a "Burst of strength" I play the Zeus card which allows me to swap cities, and by doing so I gain temple majority, do I get a fourth action this turn?
A: No. (Rio Grande)
Q: Since there are limits to the number of God cards I may hold, can I discard without playing and executing to make room for new, possibly better cards?
A: No. The only rules for discarding are by using them or by the effects of other played cards.
Q: Since I may not discard without executing, can I play a card that would have no effect by executing it?
A: Yes, provided that the conditions in the God card description exist and the instructions are followed.
Q: What does it mean that "A player may not use a God card drawn on this turn?" (p. 7)
A: A God card cannot be used on the turn that it was drawn from one of the decks. God cards are added to a player's hand and looked at only after he has finished "burst of strength". (p. 3)
The following sections describe the individual cards. Each card is preceded by its number of copies in the deck and the symbol @ to indicate if it is playable during the opponent's turn.
(2 @) After a successful attack by your opponent, move all Greeks and ships from the besieged city to one of your other cities!
So the attacker doesn't get to add ships, since he didn't capture your ships. (Rio Grande)
If you exceed the limits in your other city, the excess Greeks or ships go to your supply. (Rio Grande)
(4 @) Attack as though you had one additional Greek!
Read "Attack" as "Battle". This can be used by the defender as well as indicated by the the swirl mark on the card and the word "attack" is used for defense in Example 1 of the rules.
(3) Attack one non-adjacent opponent's city with Greeks! Greeks in neighboring cities may join in the attack.
The Chris Dorrell translation (HELLAS Cards V2.doc) makes it clear that only one city providing Greeks in the attack can be non-adjacent. Alert new players to this interpretation before playing.
The only rule hindering movement through occupied cities is the adjacency clause. This card drops the "adjacent" term from the following rule for attacking over land: "He ... may attack from all his cities that have direct routes over adjacent connected land segments to the attacked city." (p. 4) Therefore, attacks over land can be non-adjacent with this card provided there are connected land segments.
Several such cards could be used to permit several non-adjacent cities to send attacking Greeks.
It is best to play this card first before designating a battle tile. Otherwise, if it is canceled, it creates a situation where a battle is committed without sufficient greeks to win.
It is best to play this card before playing the "swap ships for greeks" card. Otherwise, if the ships were swapped so that there are more than 3 greeks on the tile, then an "attack from one non-adjacent" is played but canceled by the "void" card and there are no adjacent tiles to attack; it leaves a situation where there are more than 3 greeks on a tile at the end of the current attack phase. If this occurs, for the sake of consistency, the greeks on that tile should be reduced to three.
(2) Attack two cities, one after another!
After resolving an attack (including capturing ships, regrouping, and discarding excess Greeks), play this card to make another attack. (Rio Grande)
Since there is a specified number "two", it can be interpreted that two and only two cities can be attacked in one turn, even if another of this card is played in the same turn.
(3) Before an attack, swap as many ships for Greeks as you want in one of your cities!
After the attack is resolved, if any cities have more than 3 Greeks, return the excess to your supply as usual.
The Greeks created from ships must be used in the attack! (Rio Grande)
(2) In an attack over the water, you need just equal power to win (as in an attack over land)!
Normally you need at least one greater to win an attack over water.
(2) A flood reduces the number of Greeks to 2 in all cities in which 3 Greeks stand (both yours and your enemy's)!
Ships are unaffected.
WARNING!!! The following are some really nasty, legalistic interpretations of this card.
Since no rule hinders when, during a player's turn option, a flood card may be played; it may be played in the middle of regrouping, during a burst of strength turn option. Therefore, a player can start by regrouping his Greeks to less than three per city, then play the flood card and then finish regrouping with a city having three Greeks.
Arguably, a flood card can be played when a Greek is not in any city but moving between cities, each with two Greeks, during Regrouping. However, the game functions with Greeks having the states: on a particular map tile or in the supply box. Regrouping each Greek requires 2 states (in city A or city B) and the state of "moving between cities" is unnecessary. Since it is unnecessary and not explicitly in the rules, the argument is weak and should be considered false.
Additionally, during an attack turn option, a player can move some Greeks to a tile for battle, play a flood card, then move more Greeks before combat.
A city with legally 4 or more Greeks, for example where ships converted to Greeks before attacking, is still a city "in which 3 Greeks stand". So, don't try to cheat with this scheme.
Furthermore, on a battle tile, where both sides have Greeks, evaluate and reduce each side separately, if flooded.
The Flood Card has several loopholes. Players may want to agree that one may not be played in the middle of other actions like regrouping or combat.
(4) After a successful voyage, you may attempt another voyage!
Play several of these cards in one turn to get several additional voyages.
(2) After a successful voyage, you may place any two additional figures (Greeks or ships) in the new city from your supply!
The additional figures can't come from another city unless the supply is exhausted. (p. 7, Rio Grande) They must go to the new city. The card text interpreted literally implies you must place two figures if you use it, but the intent seems that it's OK to place only one additional figure.
(3 @) All ships in your attacked city defend like Greeks.
Your defending ships simply add power. They are not actually changed to Greeks, so if you lose, the opponent can still capture them, and if the attacker plays Flood, the ships defending like Greeks are not affected.
(2) Instead of the first drawn landscape tile, draw a new one! Place the first drawn tile under the stack.
If you draw an unplayable or otherwise undesirable landscape tile during a voyage, draw another. Since the first drawn tile is placed under the stack, it is clear that a player can not replace the first drawn tile with the second.
(3) Your voyage is successful when you have at least as many of your ships in adjacent cities.
Normally you need more ships than your opponent in adjacent cities to place the tile. You still need at least one ship to succeed, because you will turn the ship into a Greek on the new city.
(2) Draw a God card from your opponent (he must show the card backs)! If you now have more than 7 cards or more than 3 of one kind, discard the card drawn.
Otherwise you keep it.
There is a rule that "a player may not use a God card drawn on this turn." (p. 7) meaning a God card cannot be used on the turn it is drawn. However, the context suggests this only applies to God cards drawn from one of the decks. Therefore, a card drawn from an opponent using this Zeus card can be used immediately.
(2) If your opponent has more than 3 God cards in his hand, he must discard down to 3 God cards. He chooses which cards to discard!
The discard piles are apparently face-up, so presumably the opponent must show the discarded cards.
(2) Swap a city of your choice with your opponent! The players move their Greeks and ships to the new city.
You pick a friendly and an enemy city, then you move all your city's pieces to the enemy city, and all the enemy city's pieces to your city. Both cities' ownership has now changed.
Playing this card during a Burst of strength to get a temple majority will not give an extra action. (Rio Grande)
(2) Take two turns, one after another: first Burst of strength, then Voyage or Attack!
These two turns are not in addition to your normal turn. There are no terms such as "additional" or "again" and a specific number of "two" implies this card is not cumulative.
Since turn options are called before cards are played, if this card is voided, the player must continue to execute the "burst of strength" turn option.
A god card drawn in the burst of strength turn can be used in the voyage or attack turn.
(3 @) The God card just played by your opponent is voided! Discard both cards.
Simply a "cosmic zap" to cancel the card your opponent just played. The opponent can counter with a void of your void, and you could void their void that voided your void...
The player whose card was voided could play "Use a God card without discarding it!" to retain his voided card (and even play it again immediately). Use or play is the sequence: place, read, pause, execute and discard. (p. 6-7) The "void" card cancels its execution. The "use without discarding" card cancels its discard. So the card is kept.
(3 @) Use a God card without discarding it! Discard this card instead.
After playing and resolving a God card, you can discard this card instead of the played card, thus keeping the played in your hand to use again. You use this card after playing the card you don't wish to discard (not before). (Rio Grande)
The retained card can be used again immediately if desired. (Rules Example 3)
Of course this card lets you keep your own card you just played, not an opponent's card they just played.
(2) With Burst of strength you execute two additional actions!
This is cumulative with a temple majority (i.e. with a temple majority and this card you would execute a total of 6 actions). (Rio Grande) The word "additional" implies the card can accumulate with several plays of these cards.