Meh, there's several "easy" summoning fixes:
1) Each summoner can summon X points worth of stuff,especially interesting if you relate it to the cost of the summoner (e.g. a summoner can summon say three times his own cost). Limit could be per turn or per match. Per turn would be especially interesting since it'd allow things like stacking 10 "weak" summoners to summon 1 big monster, or taking 1 "powerfull" summoner to do the same.
2) You can summon a maximum of Y % of your points as reinforcements. E.g. lets say the max is 30%, in a 2500 point match you can start the match with 2500 points worth of stuff then summon an additional 833.
3) Only X% of your army may at any time be summond minions, if your summons would exceed this percentage it fails. E.g. take the 30% & 2500 points of the previous example . In the first turn you migh be able to summon 833 worth of points, but if some stuff dies and of your Original 2500 only 1000 still survives you may now only summon 300 points worth of stuff in this turn (provided you don't already have 300 points worth of summoned troops).
4) If the summoner dies all troops he summoned get badly hurt, e.g. for every summoned unit roll 2 dies, if higher than the bravery of the summoner they evaporate into thin air. Outright killing all of them might make the summoner to nice a target though. No point limit (though possibly a summoning per turn limit)
5) At the start of your turn roll a D3 your summoner may attempt that many summons this turn.
In each case, adjust summoner point cost to a sensible level...
seriously, fixing summoning might be one of the easier ones in all honesty... if I can think of 5 halfway sensible solutions in 10 minuts GW should be able to find something decent too
