Combining this with a discount effect allows you to get those cards into play quickly
Let me give you a simple example
If your curve is low enough, you should be able to reliably get back quite a few cards if youve been filling your graveyard throughout the game with self-mill or other means
In your developing turns, the flash on it offers you an amazing level of flexibility, letting you waste your opponents mana by not letting them use removal on your turn, catching your opponent off-guard sometimes (especially if they dont realise youre on Mono-Blue), and letting you hold up countermagic whilst still threatening to develop your battlefield if you dont need to counter something
Tribal Reanimator Commanders (Scion of the Ur-Dragon, Horde of Notions, Gisa and Geralf, Kaalia of the Vast, etc.) There are a LOT of commanders well suited to tribal reanimator strategies, but the 4 I have listed here exemplify what you should be looking for when narrowing down which legendary creature should be at the helm