Nilrem, Heroic Tortoss would function very similarly to the Windlord Spear logic: The player needs to periodically target and cast on an attackable Humming Crystal (69639). This places a shield buff on the player: Crystal Shell (137633). It's important to keep the buff up at all times during the encounter. Various events can knock the shield off, so refreshing it periodically during the fight is crucial. At it's most basic level, the logic would be something like "if not UnitBuffID("player", 137633) then [cast any spell on nearest Humming Crystal] then /targetlasttarget. Optionally, one could focus a Humming Crystal and cast on focus, but that's less awesome because the fight involves a lot of movement, and one may move out of range of their focused crystal.
For Horridon, the boss check would look for the debuff "Direhorn Fixation" (140946) and then periodically cast a damaging 1GCD spell on Direhorn Spirit (7068

to keep knocking it back. Ideally, they fewer GCD's you burn keeping the spirit knocked back, the better your DPS will be. This feature would involve a range check to keep the Direhorn Spirit at max range from you at all times by tossing a corruption on it whenever it came into range.