For the most worst scenario you must
DAO
Do not kill lothering bandits
Let Crows with Ignatio lived after doing all their quests...or do not do their quests and let them lived
Support deamon Sophia, Kill Avernus and not let him do blood magic experiments.
Everyone in Redcliffe being dead, Isolde lives, Connor have demon living inside him
Blehen was not supported and Branka is dead...Harromound is a king and Anvil destroyed
Do not kill dragon and The Sacred Ashes cult still running around...or do not put blood in ashes and tell everybody about urn.
The werewolves kill the Dalish clan with Zathrian
Kill all Tevinters in alianage, make Alienage elves sacrificed and make Vaughan alive...do not protect them when darkspawns attack denerim
Templars supported, Circle is annulled
Execute Alister, Loghain is a grey warden, Anora as a queen-Eamon and Connor loose all
Warden do not do ritual and die
Amaranthine burned
Kill peasants who make revolt and do not protect roads, farms and city
Warden keep was not prepared(do not do anything with keep and soldiers) and was destroyed
Architect was killed
DA2
support and help-do not kill all Templars
support and help-do not kill all Qunari
do not help apostages and nobles who fight against Meredith
do not give Isabella send Tome of Koslun in Tevinter
do not give Fenris to Danarius
do not send Feynriel to Dalish and in Tevinter
do not kill dragons near Kirkwall in mine
Make Carver as Templar or Bethany(do not make her warden or cirlce mage) was die on deep roads.
Do not support Merril and after killing abomination Merethary kill the clan, and destroy the eluvian
Do not execute all Chivaliers in Prosper Manor, support Tallis