If both are in play, you can potentially reduce the cost of any dragon you might play by four mana
While Glissa interacts with Incubator tokens, the important effect on Glissa is the one that gives Phyerxians double strike
Having two of those qualities doesn't make an object more historic than another or provide an additional bonusan object either is historic or it isn't
Codsworth, Handy Helper I really like Codsworth, Handy Helper, and lots of white decks use aura and equipment, either for utility or enchantment based removal, so both of the activated abilities are really strong
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Even if you're only looking at Commander, this allows you to put a Sol Ring directly into play, but that's probably the tamest thing you can do with this thing