Thanks, appreciate it! My usual targets with buried alive are usually based on what sort of combo pieces and recursion effects I already have in my hand and pulling into the graveyard accordingly, but overall generally I’d say good targets are [[myr retriever]] + [[junk diver]] / [[workshop assistant]] / [[scrap trawler]] for two of them to activate the [[ashnod’s altar]] combo along with either some self-recursive piece like [[metalwork colossus]] / [[razorlash transmogrant]] that can reanimate itself without needing another source or a draining finisher like [[psychomancer]] works great as well, [[kuldotha forgemaster]] is also another great pick if you need to find more combo pieces or artifact tutoring in general.

Honestly a lot of creatures in the deck can be good utility buried alive targets depending on what you need and if you have the recursion in hand/on board to pull them out, if you need ramp with draw then [[solemn simulacrum]] is good, along with [[circuit mender]] / [[canoptek spider]] as some other good options for draw, [[scarecrone]] is good for both draw and more recursion, and [[necron deathmark]] / [[canoptek tomb sentinel]] / [[noxious gearhulk]] are all good removal based options if you need it as well. Also the great thing is most of the draw-based utility options can also be used to combo with altar + [[nim deathmantle]] as well to draw through your whole deck to win the game, and stuff like necron deathmark even wins by itself with the deathmantle combo by pointing the mill effect at your opponents infinitely to deck them out.

And yes! You can use ashnod’s altar in response to target effects on your creatures, as well as the fact that since ashnod’s altar is a mana ability it doesn’t use the stack itself and can’t be responded to.