I've been thinking about this combination and think this can be very devastating! If you can take the power scroll instead of 3 channel dice and channeling staff (you can still take the 3 channeling dice), you are going to destroy hordes!
First you have to make him use his dispel scroll and and most of his dispel dice and leave at least 2 or 3 power dice (try to convince him that you can't cast anything dangerous with those dice). When the moment is right, use your power scroll and Fiery Convocation is now 10+ to cast! It can be easily cast with 2 dice but to be sure 3 is almost certain ( you don't want to fail with this trick).
Now his horde takes s4 hits every magic phase if he doesn't dispel it. Because you made sure he can't dispel it on the turn you cast it (which you should by all means!) he now have to dispel at 19+! Lvl 4 wizard must use at least 4 or even more to dispel it, probably meaning that if he rolls poor winds of magic, he may not cast anything and just tries to dispel this (and might not succeed). If he choose to ignore it than his horde would be drastically weaken.
This is not a lizardmen only tactic, high elves can do this too, but I'm not sure if they can get loremastery and guarantee that they get this spell. So what do you think? ^^
First you have to make him use his dispel scroll and and most of his dispel dice and leave at least 2 or 3 power dice (try to convince him that you can't cast anything dangerous with those dice). When the moment is right, use your power scroll and Fiery Convocation is now 10+ to cast! It can be easily cast with 2 dice but to be sure 3 is almost certain ( you don't want to fail with this trick).
Now his horde takes s4 hits every magic phase if he doesn't dispel it. Because you made sure he can't dispel it on the turn you cast it (which you should by all means!) he now have to dispel at 19+! Lvl 4 wizard must use at least 4 or even more to dispel it, probably meaning that if he rolls poor winds of magic, he may not cast anything and just tries to dispel this (and might not succeed). If he choose to ignore it than his horde would be drastically weaken.
This is not a lizardmen only tactic, high elves can do this too, but I'm not sure if they can get loremastery and guarantee that they get this spell. So what do you think? ^^