Thank you very much for replies and especially dreamlitz for putting so much effort into clarifications. On the 'continuous damage' for Vishnu, I meant when she is on the receiving end.
If this was merely a miss it would be ok. However, it is also -20 BG on a char you want to start bursting as soon as possible. A lot of times it is a question for me - burst on t3 or debuff. I could use Tish buff on her to make sure I have enough BG for both, but than Mike is too slow. Perhpas should have mentioned I don't have Shingen yet ><.You mentioned that Iris' debuff can miss, yes, but with Vishnu, it's the equivalent to guaranteed miss 'cos she doesn't bring any at all
Also, I have learned the hard way, that Sol echo healing overwrites the 10 turn regen from normal accessory set. So, here is a warning for anyone intending to burn your precious magnas on her for that purpose...
For now, I'm comparing the Lugh/Iris, Tish, Mike, Sol to see what works best for me. Thanks again for help.