When using 0 mana cost when negative smite + judgement casting smite, if you make judgement free with Foot of the Mountain + Judgement gloves smite becomes 297 mana cost and still removes mana even when you indirect cast it.
Then you can cast smite as normal giving infinite damage / cast speed with the smite amulet “devotion”.
This also leads to infinite ward with the ward gained per missing mana on traversal experimental affix.
Video of how to reproduce: Twitch