Herald of ice/siege ballista & socketed support gem help

hello I am currently using siege ballista(socketed in my bow) & herald of ice socketed in my body armor. i know herald of ice works with siege ballista but I am wanting to know if my support gems work as well connected to herald of ice through siege ballista. the support gems I am using are knockback support, added fire damage support & chance to poison. does this work the way I think? also I know 1 support gem can assist multiple skill gems if socketed together but can 1 or more support gems assist 1 skill gem if they are all different support gems. Lastly I would like to know if cruelty support can work with poison support if both support gems are connected to herald of ice & if that combo works through siege ballista in the configuration described above? thanx

The way you have worded it is a bit funny, but the damage added to your siege ballista skill by the herald is also increased(decreased) by the support gems connected to the siege ballista skill. Supports connected to herald of ice may make the herald more powerful, but it's not like adding a whole new string of supports to the siege ballista. POB can be a good way to confirm these interaction if you are learning and want to know how things interact beyond the tool tips provided in the game.

It is possible to support heralds and aura with certain supports, to increase their power, doing this will also usually increase their reservation cost.

The way herald of ice works is it is doing 2 things. It creates an explosion, when you shatter an enemy, you can modify this damage amount or use it to proc other effect through support gems(and other methods such as skill tree). It is also buffing all spells and attacks you do without them needing to be connected to the gem. Siege ballista is an attack (works for totems) so it is getting buffed. That damage from the buff is multiplied by every that is effecting your siege ballista's, its not just flat damage on top.

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also I know 1 support gem can assist multiple skill gems if socketed together but can 1 or more support gems assist 1 skill gem if they are all different support gems.

Yes, so long as the skill are able to interact (this is not always true), multiple support gems can assist one skill gem and a support gem can support multiple skill gems, if they are linked together.

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Lastly I would like to know if cruelty support can work with poison support if both support gems are connected to herald of ice & if that combo works through siege ballista in the configuration described above? thanx

You can connect those support gems to your herald of ice in your body armour. They will increase the amount of damage the Herald of ice skill is doing, but won't increase the amount the herald buffs your siege ballista's. There are some mods on gear that can increase that buff, but that's a bit more advanced. If you do want to buff your herald of ice skill, there are probably some better options, just remember you need to be shattering enemies for this to be proccing.