A couple questions

How many times can you use an ongoing effect a turn? For example with Wrest the Mind from Visionary you can redirect damage from one target to another so with Grand Warlord Voss can you redirect the 3 damage back to GWV and then redirect the 2 damage to GWV?
Also does this count as Visonary dealing the damage or the original person dealing the damage?
For cards that say “if the target leaves play, destroy this card” if the villain flips does it destroy that card?

Gaarus, I’m going to address each of your questions in order.

The only restriction on number of times things may be used comes from the “play 1 card, use 1 power, draw 1 card” rule for the hero turns. Other than that, it’s based on what is written on the cards. Thus, cards that damage attackers, like The Wraith’s “Combat Stance” or Ra’s “Flame Barrier” deal damage only in response to the FIRST attack each turn. But in the case that you presented, concerning The Visionary’s “Wrest the Mind”, you may use it as many times as you choose to, redirecting both of Grand Warlord Voss’s attacks. Please note that each usage deals both Grand Warlord Voss and The Visionary 2 damage, as per the instructions on the card.

Redirecting damage does not change the source of the damage. This is important, as it does not mean that damage gets boosted by any modifiers which on the damage dealt by the target redirecting the damage.

When a villain card flips, it is not leaving play. It is still in play, just in a different form. Therefore, cards affecting it are not destroyed.

I hope this covers everything! If not, feel free to clarify further!