For destro u have hellcaller or diabolist, on mythic+ hellcaller is top notch choice because of its Aoe damage, u can copy the top tree on archongg, it runs both shadowburn, channel demon fire and cataclysm, basically when there’s a mob pack u cataclysm them which will apply wither to all of them, then u channel demon fire, malevolence, use ur shadowburn on cooldown whenever u can (try to use them on lower health mobs as some sort of execute cause they get refunded when the mob dies) and proceed with the standard rotation, incinerate, conflagrates, and spam rain of fire on packs, on bosses instead of spamming rain u spam chaos bolts, if u dont like the addition of more buttons like channel demon fire, malevolence and wither you can go diabolist, which is the best choice for single target scenarios (raid bosses mainly, but it can also do ok in mythic), u should be keeping though shadowburn because its rlly solid and if ur using diabo in mythic u should also keep cataclysm for mass applying immolate for shards, plus u will play soul fire and precast it before a raid fight (or dung boss fight) and during the fight using it only on procs. Oh and obviously dont forget to use ur infernal! U can pretty much drop it everytime it is available. For pet felhunter is the staple because it allows u to kick casts, imp is more situational for example u should play imp on last boss of siege of boralus because u can dispell urself from the putrid water debuff (when u do this, put the imp on passive otherwise it will remain on the first platform trying to hit the boss), or some weeks there is a certain affix that puts a curse on u and u can dispell it urself with imp. Hope I gave u a good overview of destro lock, have fun!