T2A Spawns and Locations

Spawns

Vermin Horde (rats/slimes- despise) Easiest for a small groups, crashing sucks, and you need to wear savage paint.
Arachnid (spiders-Teth keep) OK for small groups, bring a tamer and mages, find a safe ledge.
Cold Blood (lizards-destard) OK for small groups, need a tamer or provoker and mages.
Unholy Terror (ghouls-deceit) Takes too long with a small group as well
Abyss (imps-Fire) Too hard for small groups
Forrest Lord (pixies) Takes a ton of people and good karma.
Locations
T2a has 12 locations, 2 up in the ice areas, 2 in the desert, 1 on the island across from the desert, and the rest south of the desert. The spawns you get at each is random, but it seems that some spawns are more likely than others at certain locations.
Ice West (1)

Use Ice dungeon, or the teleporter by old Minax base. Advantages: Easy to get to. You can use a boat, but it takes too long to lead the spawn to the boat to really advance the spawn this way. Disadvantages: Rather spread out making it kind of hard for small groups to advance the spawn very far.

Ice East(2) Take a boat from the Lighthouse, or use the teleporter half way between the Tortoise alter and Delucia to get here. Advantages: Not as spread out as Ice-west and you can park a boat at the alter, making a boat usable here. Has a teleporter a few steps East of the alter which takes you to a few screens NW of the alter. There is also a teleporter near where this one takes you, but do not use it unless you're trying to get to the Damwin alter. (I think the teleporter was supposed to go to the area that is east of the rock wall dividing the Ice-East area, but it's broken and going to the wrong place.) Disadvantages: Hard to get to. There is a rock wall that divides the Ice-E area and stuff spawns on both sides and you need to take a boat between them.
Oasis (3) Use the Lighthouse or Fire dungeon entrances. Harder to get to than some of the others, but easier to keep private.
Desert (4) Use Fire dungeon or run North from Glow/Papua magic shop portal.
Terra Sanctum(5) Take a boat from Papua, the lighthouse area, or the coast by the Fire dungeon exit to get here. Advantages: Easy to keep your spawn private here. Disadvantages: Hard to get to, spread out, gets the harder spawns more often.
Marble (6) Use Marble island entrance. Easy to get to, but people tend to run by here lots and join your spawn. Several areas trap people, so bring lots of red pots.

Damwin (7) Use Marble Island entrance. Run south on the road, it's the second alter. Gets the Rat spawn more than the others.
Hoppers (8) Use Glow/Pap magic shop portal or Vesper Cem. Run to the swamp SE of old the Minax base. Can also use Minoc mines entrance. Lots of safe ledges to teleport to. Annoying plague beasts and other spawn already here, which makes it a pain.
City of Dead(9) Use the Trin passage, red line. Can safely teleport onto building from ledges, and do the entire spawn from there.
Wild (10) Use Vesper Cemetery. The Oaks spawn. Need good karma here.
Khaldun (11) Use Island Temple or Vesper Cem to get here.
Tortoise (12) Use Island temple or Vesper Cem to get here. This one seem to get the rat and spider spawns a lot.
Red Guide to T2A
Vesper Cemetery, Passage to City of Dead, and Ice Dungeon are the entrances that are safe for reds on their way to PK, or do Spawns in T2A. The Lighthouse, Fire Dungeon, Marble building, and Passage to Minoc Mines are fairly safe, however guards can be called on you, so try them at your own risk. Runes to all listed below can be found in the runebook Athene's small tower (in front of FL Keep). The runes in the book are colored. If you're Red, only use the red runes, or the yellow ones at your own risk, but do not use the Blue runes.
RED SAFE:
1. Passage to Delucia
Use the Red path in the picture, which goes directly to the city of the dead. The Passage to Del has 2 exits, the North and longer path goes to the City of the Dead, the southern one goes into Delucia. Reds can safely use the red path.

2. Vesper Cemetery

Goes from Vesper Cemetery to T2A (between Champ 8-Hopper's, Champ 11-Kaldun, and Champ 10-Wild).

3. Ice Dungeon

Goes from the ice Dungeon entrance North of Wrong to Champ 1 (Ice-West).

Use with Caution:

These entrances border, or are in guarded zones. You can use these (I went and tested them in both directions. I even went up to the guards at the Island temple and said "hi" to them (on my red), and wasn't guard whacked). Keep in mind though, that someone can call guards on you at these.

1. Island temple

To get to Champ 11 (Khaldun) and Champ 12 (Tortoise)
2. Marble Island To get to Champ 6 (Marble) and Champ 7 (Damwin)
3. Yew Lighthouse Pass

To get to Champ 3 (Oasis) and the coast to launch a boat to Champ 2 (Ice-E)
4. Fire Dungeon

To get to Champ 4 (Desert)

5. Minoc Mines Passage To get to Champ 8 (Hopper's) and Champ 11 (Khaldun). Mark your rune here, inside the passage, to keep out of the guard zone.

NO REDS
1. Glow/Pap Portal

To get to Champ 8 (Hopper's)
2. Passage to Del (Blue line) Second choice way to get to Champs 9, 10, and 12
3. Brit Sewers To get to Champ 8 (Hopper's)