Crown of Thorns and Elijah's Mantle are ongoing as long as they're active, because they're artifacts and don't specify otherwise.
Covenant with Salt and Plagued with Diseases are ongoing when played as artifacts and instant when played as an enhancement. Yay for confusion. They end when deactivated as artifacts, or are permanent when played as enhancements.
Covenant with Adam is ongoing as an artifact, and ongoing as an enhancement because it has a specified duration.
Sword of the Spirit (CoW), Joy (EC), Broken Cisterns (RA), and Testing of Job (ROJ) are ongoing, because they are tied to the place ability. They end when they are no longer placed.
Lystra (Ap) and Jerusalem (Ap) are ongoing, because they only increase while the specified characters are blocking. They end when the characters are no longer blocking.
Other increases/decreases that have a specified duration (usually end of turn/battle) are ongoing. See Faith of Children, Plague of Flies, Hunger, the Trumpets from Warriors, Burning Censer (C), etc. They end when the end of turn/battle/whatever happens.
Letters to the Philippians is instant, because it is stated to happen on activation.
Gates of Samaria is instant, because fortresses are not mentioned in the ongoing section.
Increases/decreases on characters and enhancements that don't have a duration are instant. See Gib Trick (Pa), Bildad the Shuhite, Devouring Birds, Burning Censer (FF), Faith of Noah, Strengthening Angel (Di), etc.
All instant increases are permanent.
I don't particularly want to post abilities, because that's a lot of cards. I just filtered the special ability column of the
Redemption Card List from Land of Redemption to find "increase" or "decrease" and posted some examples. I didn't search "gains", which some older cards use instead of increase, like Elijah's Mantle, but mentioned some I remember off hand.
That should cover most scenarios, I believe.
