If you think about it, if you have bkb up the only way they can break linkens is by using a debuff immunity-piercing spell or item, so situationally it can be very good and probably the only way for your hero to play a game sometimes if no backup from team (think bloodseeker rupturing a faceless void).

Bkb if you’re being chainstunned and nuked in team fights.

Linkens if you are protecting against charge, duel, or blink hex.

Euls if you are support, and a few cores who need a dispel

Manta to debuff roots or silences.

Satanic for the same as Manta, but allows you to brawl

Aeon, if you are being instakilled and non of the above will save you. And they haven’t gotten nullifier yet

Shadowblade/silver edge if they have nullifier

anything that hinder what you want to do and you know how to counter it but not doing it means you are stupid, just do whatever need to be done.
Playing Magnus/ Enigma is common going for both especially against Rubick/ any insta cast heroes like Lion/ Shaman. When you play against good player of these heroes, it’s LK + BKB is more essential so you can do your stuffs.

when there’s heroes like pudge, bane and LC paired with heavy disable team. sometimes you need to sacrifice damage so you won’t feed as core

I buy linken by default in this SB meta, if the enemy has 1 or 2 more disables I gotta go BKB too

i rarely buy both unless my hero is exlusively based around mechanical utility instead of damage. against pudge+PB there is pretty much no use in going for bkb

morphling says hello

Yes if you’re engima and they have a rubick. If they have a bkb piercing spell you have to deal with but the enemy doesn’t have a bkb piercing spell to break linkens.

I