They then Tribute monsters whose combined Levels are equal to or greater than that of the Ritual Monster (though sometimes exact matching is required), or fulfill other conditions stipulated on the Ritual Spell Card to Summon it
Which in turn means that: If there's a third effect, Event C, that happens whenever Event A happens, And Event A gets replaced by Event B, Then Event C won't happen either (because Event A never happened), Third, replacement effects only modify an event once
This currency is obtainable for free via the game missions and step-up battles
One time, during the rest of this turn, if either player(s) rolls a die (or dice), you can have the player(s) re-roll
This may be a good time to pick up 1 or 2 of these for investment purposes if that is your thing, or perhaps you just want them for your collection (I wouldnt blame you)