One thing I found with the design of multi-initiative solos is the strange effect until the end of next turn powers have on them, both from the PCs and the Solo it self.
For instance in your creatures second form its Glimpse the Unthinkable power stuns its targets until the end of its next turn. Now if it uses it on initiative 50 it will end after its turn on initiative 30, this means that any PC with an initiative of 29 or lower will still get to act in the round that they were stunned.
Also creatures who act on multiple initiative counts are more sustptible to player until the end of next turn effects as they are basically getting double milage from those effects.
Another strange phenomenon is that a multi initiative solo can also take ongoing and zone damage twice (or more!) each round. If a PC lays down a zone that deals 20 ongoing damage to any creature starting its turn inside it then the solo can actually end up taking double, or two lots of 20 damage.
To begin with when countering some of these effects I changed the solos own powers to "until the end of its next turn on the same initiative score" which solved the timing issue and made its own powers last the expected amount of time. But there was still the issue of plater effects, so ultimately I used the system that a few creatures adopted in MM3 and gave had the solo just acting on one initiative but giving it more actions. For my campaign end boss (now posted as an example) I used "minor, move, standard and two basic attacks" and "minor move and two standard actions". This works quite well as it is easier to run and all powers on both sides work as normal.
For instance in your creatures second form its Glimpse the Unthinkable power stuns its targets until the end of its next turn. Now if it uses it on initiative 50 it will end after its turn on initiative 30, this means that any PC with an initiative of 29 or lower will still get to act in the round that they were stunned.
Also creatures who act on multiple initiative counts are more sustptible to player until the end of next turn effects as they are basically getting double milage from those effects.
Another strange phenomenon is that a multi initiative solo can also take ongoing and zone damage twice (or more!) each round. If a PC lays down a zone that deals 20 ongoing damage to any creature starting its turn inside it then the solo can actually end up taking double, or two lots of 20 damage.
To begin with when countering some of these effects I changed the solos own powers to "until the end of its next turn on the same initiative score" which solved the timing issue and made its own powers last the expected amount of time. But there was still the issue of plater effects, so ultimately I used the system that a few creatures adopted in MM3 and gave had the solo just acting on one initiative but giving it more actions. For my campaign end boss (now posted as an example) I used "minor, move, standard and two basic attacks" and "minor move and two standard actions". This works quite well as it is easier to run and all powers on both sides work as normal.
