Thinking about Offering like it's letting you play an entire extra turn gets you about halfway to understanding its Strength, but keep in mind also that Ironclad has cards which care about filling your hand, like Armaments+, Fiend Fire, and Second Wind, for which being able to draw 5 with an Offering+ is tremendously strong. Getting your Rare Powers into play without taking a ton of damage is also often a big deal.
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