There are many friendly NPCs that you can kill (betray) on the first floor of the Battle for Stormrise campaign. Be careful; attacking them will turn them against you. When you kill them there is a chance that they will turn in to a "ghost". Take your time and only attack a friendly NPC when they are on low health, and you have other friendly NPCs nearby to help fight them.
Easy "Loveable Rogue" achievement
Any creature that does not attack you and has an asterisk next to their name is considered an ally. Play the "Battle for Stormrise" map. Many guards, dogs, servants, etc. will spawn in various rooms. Protect all NPCs with an asterisk next to their names until you have eight following you.
Easy "Ultimate Warrior" achievement
This does not need to be completed in a single quest. Unlock as many classes as possible in order to take advantage of their better starting stats. Then, choose a stat that you will focus to progress in earning ""Ultimate Warrior". Raising that stat over anything else. Take your time going through each level and loot every container that you find. If you find a potion, check the name before you drink it. Some will help by raising a stat, but others can cause a setback. The hardest stat to raise will be your hit points. Avoid close combat and rooms with large numbers of enemies. Use doorways as choke points to limit the number of enemies that you have to face at once. Collect as many healing items as possible. Avoid campaigns that feature enemies that use poison, which will drop your health by 1 HP per turn until you can get cured. Consider using a ranged class, including mages to earn "Ultimate Warrior", however highly armored melee classes can also be used. However because some enemies also use ranged attacks you can lose a lot of health trying to get close to a monster.