Can someone explain the Caustic Arrow change?

I am sort of confused by it, not that I am all that smart to begin with. Is it a buff? What is the physical attribute associated with it? And what ascendency would you pick to play it as a starter?

This is a monster buff for Caustic Arrow. In greater detail:

* Caustic Arrow's Dot effect is no longer a 'cloud'; it's an Elemental Ground effect like Fire Trap, Flame Dash, or the map mods. This is to make it easier to tell where the boundaries of your corrosive DoT effect are, and to take advantage of the optimization of Elemental Ground effects Grinding Gear's done.

* Caustic Arrow's Caustic Ground effect does (a shitload) more damage-per-second than it used to, but it doesn't last as long. Any given click of Caustic Arrow should do roughly the same damage, but you do that damage a lot faster. This means you need to click more often, but it's also a gigantic DPS buff and should make killing bosses with Caustic Arrow much better. No more waiting ten years for poo gas to drop Act bosses.

* Caustic Arrow now also causes an AoE explosion on any enemy it hits, and at its final destination point where it triggers Caustic Ground. This AoE explosion is an attack and can cause on-hit effects or kill enemies by itself, and works like any other attack. The higher your weapon damage, the more damage the explosion does; the higher your attack speed the more explosions you can shoot. Accuracy determines whether the explosion (but NOT the Caustic Ground effect) connects and deals damage, like any other weapon attack.

* Caustic Arrow does not target enemies - it targets the spot on the map where you click "Fire Caustic Arrow". This means that you-the-player can control where Caustic Arrow detonates and creates its Caustic Ground, placing Caustic Ground wherever you want and also allowing you to place its explosions wherever you want. This means you can use sources of extra projectiles, like Lesser or Greater Multiple Projectiles or the Reach of the Council bow, to create multiple explosions that overlap and can hit the same target multiple times. Other skills can do this, but very few of them allow you to pick exactly where the overlapping explosions happen the way Caustic Arrow does now.

* Caustic Arrow deals 100% Physical damage, which it then converts 60% of to Chaos damage. If you're unfamiliar with conversion, this basically means Caustic Arrow can scale both Physical and Chaos damage types and gain benefit from both, as well as being able to benefit from Unholy Might and other physical-as-extra-chaos mods. It's a straight buff to Caustic Arrow.

* Pathfinder is specifically built to use chaos bow skills like this new Caustic Arrow well. Deadeye is very good with projectiles and can work acceptably for most any projectile-based skill. Trickster has excellent synergy with any damage-over-time focused build, such as Caustic Arrow.

My personal choice, however, would be Scion with the Deadeye and Trickster Miniscendancies. Ascendant Deadeye gives you most of the most important bonuses from Deadeye and Ascendant Trickster gives you most of the most important bonuses from Trickster, and the Scion is positioned to grab more defensive stats more effectively than either straight Ranger or straight Shadow is. You get the best of all worlds and have a very strong and flexible base to build your character on.

Short version:

1) CA's damage over time got buffed a lot, slightly more than doubled (but the duration is shorter, so you'll do better DoT dps but have to maintain it more).

2) Whenever CA's projectiles hit a target or detonate at the target location, they now release an AoE hit alongside spawning the DoT ground. This means you can use CA in a similar manner to Vaal Burning Arrow (with less damage), using multiple arrows (and pierce/chain/fork if you want) to create overlapping hit explosions at the target point and on contact with any enemy along the way.

Thank you for the long and detailed explanation; way more then I could have hoped for and even I understood it, ( That says a lot ) thanks a TON