Originally Posted by LadysKnight
Liandry's DoT is % of current health. BFT is % of total. BFT is superior
Liandry's is good for tagging people at full health and then letting the DoT tick (aka shrooms), it's bad for an actual throwdown where you're trying to kill the enemy, as the damage gets progressively lower as you get closer to killing them (aka actual teamfighting). Plus, the item itself is not so great for casters as it has no CDR.
So putting them both on the map would either mean letting them stack which would be awful (double DoTs and even more flat pen? No thanks!) or making a 'trap' type item that is just massively inferior to BFT.