After finding the mage in the Source Temple, during the "Follow the Wizard" quest, you have to get back to the End of Time, where Zixzax will lead you to the last room, called "First Garden". When you go through the portal there won't be coming back - that is why you must make sure that you are absolutely prepared, and that you have plenty of potions (especially resistance ones) in your inventory. You can purchase potions from the merchant, in the End of Time.
Go through the portal, and after a short while you will find yourself in a dark room. You won't have to fight with anyone here, and the area is clear off traps. Your only task here is to select the appropriate dialogue options during a "conversation" by subsequent portals - should you select the incorrect answer, your party will be teleported to the very beginning of the area.
- First Portal - dialogue number 2
- Second Portal - dialogue number 3
After a short while Leandra will show up. When you regain control over your party, go through the portal the witch used to escape, and you will soon arrive at a new location.
Go to the building located to the north of your actual position. Speak with everyone inside and ignore all the barrels and items scattered around, as you won't need any of them, and then go to the southern section of the building. The doors on the left side are closed, which is why you have to approach the ones on the right and bust through them with attacks. Get inside the room, wait for the cutscene to end and then leave the room, heading straight ahead, where you will be visited by the witch yet again.
Go to the underground level and head to the eastern section of the room. A book called "Koob fo Setalucammi" can be found next to the wall. Open it and collect the key hidden inside. The witch will appear yet again, and when you regain control over your party you must get back to the upper floor. As you've probably guessed, you have to go through the previously locked doors on the left side. You now have to go through a couple of rooms, by going through portals highlighted with a purplish outline - "click through" them until you get to a room with portraits of fish hanging on the walls, and a passageway blocked by a barrier.
The button that allows you to lift the barrier can be found behind one of the paintings, or to be more specific, the one located to the right of the table. Interact with the painting and wait for the button to show up, after which you have to press it. Go through the freshly opened passageway and head north. Don't run to the end of the corridor - turn to the right (or left, depending on your camera settings), leave the building and continue straight ahead, until you reach an altar with Astarte lying on it.
Speak with the woman and then use a fire magic, to set her dead body ablaze. After a short while you will be able to collect the key from her burnt corpse. Do that, get back to the corridor and head all the way to the north, while opening the doors at the end of the corridor with that freshly acquired key. Make sure that you are well prepared - after getting to the upper floor via the stairs, you won't be able to get back, and you will soon face a boss called Trife.
Boss - Trife
At the very beginning of the encounter, the boss will summon three demons - it's important to refrain from attacking them with characters using Tenebrium weapons, because they are highly resistant to that metal and will be healed instead. The best approach is to use your mages to get rid of the summoned foes, while your warrior and other "physical" classes are engaged in combat with the boss itself. If you are able, you can try to "clutter" the summoned enemies together (with the help of, for instance, a teleport spell and/or scrolls) and then unleash a powerful AoE spell (like Meteor Shower). A single, top-tier spell will almost always kill them all.
Trife itself is not all that powerful, because he lacks any serious damage, but on the other hand he's fairly resistant and can stun your characters with his lightning-oriented attacks (which is why a high resistance to electricity is crucial here). The boss is complete immune to air magic (as well as stuns from lightning), but all the other resistances are quite low, which means that you will be able to do a large amount of damage with the help of remaining elements.
The biggest threat is the ability of Trife to summon assistants. Those are (summoned each turn, in this very sequence): Arhu, Icara, Zandalor and Zixzax. Each one of those characters can use their respective abilities, which in turn means that they are more troublesome than the boss himself. In general:
- Arhu - is immune to air and uses a lot of spells from different schools.
- Icara - she lacks any immunity, but can cast invulnerability spells on her companions, as well as use powerful healing.
- Zixzax - uses haste and slow spells, as well as an AoE restoration one, meaning that he and Icara should be your top priority.
- Zandalor - similar to Arhu, casts a lot of different spells and is immune to fire.
During the encounter you should focus on eliminating the ghosts summoned by Trife (use your mages and/or a ranger with a lot of elemental arrows), and use your tank to keep the boss' attention off your party. Remember to use all knockdown effects available - the boss is surprisingly vulnerable to it, and a stunned boss won't be able to summon any assistance, making the whole encounter a lot easier.
If the encounter drags on for too long and there are several summoned heroes on the battlefield, you should focus your attention on Icara and Zixzax, who can heal others, and when they are down take care of the rest.
When the encounter ends, pick up the items dropped by enemies, heal your party, redistribute elemental resistance potions between your character and head north, where you have to destroy an object called "Rorroh Latsyrc". After a short while your party will be transferred to the proper section of the gardens. Go upstairs and through the portal, and in the next area run down, where another boss fight, with Leandra and her underlings, awaits.
Boss - Leandra
This encounter is definitely one of the most difficult in the entire game. The Witch will begin by summoning three demons, Vaeg'rym, Aern'vuul and Yarl'oggoth. What is more, those demons will cast an invulnerability spell between themselves - at the beginning, those will be cast on two demons and Leandra herself, making her immune to your attacks.
To be able to inflict any damage on the boss, you have to eliminate the demons one by one, in a specified order, starting from Yarl'oggoth. When the demon is dead, one of the other two will have to use his invulnerability spell on Leandra, meaning that he will now be vulnerable to your attacks. Now you must get rid of Aern'vuul, and then the last one, Vaeg'rym. When you accomplish this, the Witch will be vulnerable again.
As you've probably guessed, it won't be that easy. Leandra, aside from demons, will also summon a group of Death Knights (which are, fortunately, without their typical invulnerability). It's worth to get rid of them as quickly as possible, when they are still grouped - a single, powerful AoE spell (like Meteor Shower, or Hail Storm) is more than enough to get rid of them. The Witch needs two more rounds to be able to summon them again.
Don't forget about your own defense - most of the enemies will try to get to your back line, so it's generally a good idea to summon a couple of monsters / elementals to keep the enemy attention off your mages / ranger.
When the encounter ends, Icara will alter her appearance, as well as give you an item - Death Knight Control Wand. Use it to learn a spell, that will allow you to dispel the barrier on the portal. Use it to go to the other side and continue your journey along the only pathway, until you reach a group of Death Knights. Use the recently acquired spell to get rid of enemies with a single strike.
When everyone is dead, collect the items they dropped and continue. You should soon stumble upon a merchant, Brian. Use the opportunity, as you won't have the chance to trade after this point. When you're done, go to the lower floor, where, after activating the God Box altar, you will encounter the last boss in the game, the Void Dragon.
Boss - Void Dragon
This is the last fight in the game, so use your equipment, potions, arrows and grenades, as you won't be needing them anymore. As soon as the encounter starts, the dragon will attack Astarte and summon a large amount of monsters. You have two objectives during this encounter - protect Astarte (if she dies, you will lose) and kill the dragon. Remember to use your summons to aid yourself in battle.
Send your warrior (or two of them, if you have a party like that) to the dragon, so that its kept away from the rest of your team. Remember to make sure that your warrior has extremely high elemental resistances, especially the air one, so that he won't be stunned by the boss' attacks. Astarte will support your party during the encounter, mainly by healing and casting Bless, which will allow your characters to hit the boss more frequently.
When your warrior(s) keeps the attention of the dragon away from your team, use the rest of your party to eliminate the summoned monsters. It's worth to use earth-based spells and attacks here, as the enemies are highly vulnerable to them (-50% resistance to earth). If you have the Earthquake spell at your disposal, use it now - it will be able to reach from one side of the arena to the other, and will deal huge amounts of damage to the enemies. Additionally, this spell has an extremely high chance (300%!) to knockdown enemies, meaning that majority of them should probably be lying on the ground (or dead). Don't mind the oil surface that you've just created - almost no one uses fire spells here (and you won't need them as well), so you should be relatively safe.
Surprisingly enough, the Void Dragon is vulnerable to stuns and knockdowns, which is why you should use those abilities as often as you can, to reduce the effectiveness of the lizard. The enemy will summon more monsters every few rounds, so remember to use Charm Arrows, and the charming effect in general to take control over at least some of them. When the enemy is down, a short cutscene will initiate, after which you will be moved to a new location.
Go straight ahead, and you should reach a building guarded by two soldiers. When the conversation with them ends, get inside the building and speak with Zandalor. If you wish to, you can speak with the remaining characters, and when you are read, go through the passageway located to the west. After a number of steps, your two main characters will start a conversation, and when it ends, the game will be completed.