Forum adverts like this one are shown to any user who is not logged in. Join us by filling out a tiny 3 field form and you will get your own, free, dakka user account which gives a good range of benefits to you: No adverts like this in the forums anymore. Times and dates in your local timezone. Full tracking of what you have read so you can skip to your first unread post, easily see what has changed since you last logged in, and easily see what is new at a glance. Email notifications for threads you want to watch closely. Being a part of the oldest wargaming community on the net. If you are already a member then feel free to login now.

Obvious advantage is you can summon whatever is needed. The rock to the opponents scissor. If its not on the table it cant be shot at T1. Summoning can never fail, you roll, and whatever fits you roll can be summoned (following summoning rules). You are not limited to three same datasheets. Downsides have already been said.

The master of possession allows summoning in the psychic phase with a psychic power, after moving. Warptime him forward, cast the psychic power, summon whatever you can.