Title: The Archmage of Arda
Author: Archmage.Potter
Rating: T
Genre: Fantasy
Status: Complete
Library Category: Alternatives (Crossover)
Pairings: Various
Summary: With basilisk venom and phoenix tears within him, Harry's body, spirit and magic is transformed and his lifespan is greatly increased. So, when given the chance to go to another universe where he would be able to grow in peace with other immortals around him, Harry accepts it, and finds himself near Rivendell at the start of the Third Age of Arda.
Link: https://www.fanfiction.net/s/13407891/1/The-Archmage-of-Arda

An entertaining OP!Harry LotR crossover. Too many contrivances and weaknesses in the writing/plotting to be library-worthy, but a fun curb-stomp nonetheless.

My (spoiler-filled) review from FF.Net:

Spoiler

An entertaining story. I enjoy the ambitious scope and timescale of the story as well as the theme of creating new communities, objects of power and legends which will echo through time.

Nonetheless, I feel like there are a few things that get in the way of the story achieving greatness.

The first is an inconsistent tone. At times the prose adopts a grand, very formal tone like Tolkien. At other times the narrative tone is chatty, using modern slang and turns of phrase. I think really you should pick one and stick with it.

The second is an inconsistency in Harry's ability/power. At times he's absurdly OP, such as possessing the Flame Imperishable; at others he seems solidly ordinary. Similarly, at times his power seems to be highly spiritual in nature, like the "native" magic of the LotR universe, whereas at other times it has the casual whimsy of the HP universe. Again, I think it would have been better to pick a single option and stick with it: either Harry's magic should adapt to his new world, becoming less flashy and more subtle (but not necessarily weaker), or it should have kept its HP nature without adding on spiritual extras. Trying to both results in a certain clash of tone.

The third is frequent narrative contrivance. The story follows a certain pattern of building up a conflict or creating momentum towards an event - and then offering up some very contrived reason to remove Harry from following through on that story. He builds Fornost, but then falls into a meditative state to avoid seeing that story through. He discovers he has a son and frees Arnor from pretenders, but then is banished to prevent him from seeing that story through. He founds Salazar, but then Eldacar turns up to force him to leave. He goes to create his centre of healing, but then the Balrog waking prevents him from being there for its operation. He and Arwen come together, and then he is whisked away by magical forces.

These things happen with such predictable frequency that the reader begins to see through the narrative to perceive the author's hand holding the strings. And the hand which the reader perceives is one so concerned with covering the thousands of years of the story's scope that it shies away from telling any single narrative arc in a complete or fulfilling manner.