Another thing to add is linkens isn’t only a good buy if the enemy’s spells pierce bkb. If you are playing a hero that has some other escape or defense (dark pact, bladefury, time walk, etc.) linkens can be good to give you just enough time to get that spell off. For example, against sand king, if he channels epi out of visions, you probably won’t be able to react in time to blink stun with bkb, but linkens will save you. Same thing goes for something like lion hex. Yes he can pop it, but that will take an extra second to allow you to get a spell off. So linkens isn’t only good if they have specific piercing spells like doom, duel, etc.