except those cost more than his whole set up and he doesnt need them

get a wand with life tap charges (shop from a5 malah)
when you go into trist go up+left first, and pull meph out by himself, pre tap and use salv to smite him down
go to town and heal, get more pots if needed
next go around to the bottom, pull baal out by himself, pre tap and use sanctuary to smite him down
go to town and heal, get more pots if needed
rush in, pre tap and use fanat to smash diablo

~1-3 min and no problems

Yes he does. You can buy all 3 for under 20 fg.

aka, more than his whole set up... and i assume he's ladder anyway where all 3x would be significantly more

but no he doesnt, its more than possible to easily uber even with a worse set up than he currently has

gl getting Lo ber vex ohm mal ist ist um for 20fg in ladder.

is there a full build guide for this please?

your eq is just fine.

Maybe try get some ress charms to inv.