I’m sorry. In Classic WoW, if you choose a talent that increases resistance to “interrupt effects”, what specific spells does that provide resistance to (the “Blessed Recovery” talent on the Discipline Priest talent tree uses the term “interrupt effects”)?
assuming you mean ‘healing focus’ as ‘blessed recovery’ is just passive healing from being crit.
it is referring to spell pushback which was much more severe in vanilla. a very fast attacking enemy like a hunter pet (<1s possible) or feral druid (1s) could make casting even a 1s spell take 3-4s.
aoe/cleave also would push you back on cast time so in general it allows you to heal under fire.
The 20% change to resist “Interrupt effects” on Martyrdom (I think this is the talent you actually meant?) is to do with lock out. You will resist kick/pummel/counterspell etc lock out 20% of the time while it’s up (you’ll still be Silenced by Imp. Counterspell).
Its related to spell push back when you get hit while casting. It’s important for priests so they can get their big heals off in a pinch.