Glamerdye's effect has no duration. It will last until the game ends or the affected spell or permanent leaves the relevant zone, with the following exception: If Glamerdye affects an artifact, creature, enchantment, or planeswalker spell, it will also affect the permanent that spell becomes when it resolves.

You choose the two color words when Glamerdye resolves. You can't change a word to the same word; you must choose a different word.

Glamerdye changes only words actually printed on the spell or permanent (if it's a card), words that are part of the spell or permanent's original characteristics as stated by the effect that created it (if it's a token or a copy of a spell), or words that were granted to the spell or permanent as part of a copy effect. It won't change words that are granted to the spell or permanent by any other effects. For example, if an Aura grants a creature protection from blue, you can change that to protection from red by targeting the Aura, but not by targeting the creature. Glamerdye also can't change what color was chosen for a permanent (such as Painter's Servant) as it entered.

Glamerdye can change color words preceded by "non." For example, if you have it change "red" to "green," it will also change "nonred" to "nongreen."

If the active player casts a spell that has retrace, that player may cast that card again after it resolves, before another player can remove the card from the graveyard. The active player has priority after the spell resolves, so they can immediately cast a new spell. Since casting a card with retrace from the graveyard moves that card onto the stack, no one else would have the chance to affect it while it's still in the graveyard.

Glamerdye can't affect the keyword fear.

When a retrace card you cast from your graveyard resolves, fails to resolve, or is countered, it's put back into your graveyard. You may use the retrace ability to cast it again.

Casting a card by using its retrace ability works just like casting any other spell, with two exceptions: You're casting it from your graveyard rather than your hand, and you must discard a land card in addition to any other costs.

Glamerdye affects each instance of the chosen word in the text box of the spell or permanent, as long as it's being used as a color word. Glamerdye won't change such words in card names, such as White Knight. It also won't change mana symbols.

A retrace card cast from your graveyard follows the normal timing rules for its card type.