I'm quite enjoying Lina Ice Ball (rolling ball thing), but so far I've chosen not to upgrade it.
Completely un-upgraded it costs 10 rage, if I upgrade it the cost goes to either 15 or 20 (can't remember), but the damage / hit points only goes up slightly (about 10%?).
Even at level 1 the Ice Ball seems pretty hard for the oppositon to kill.
In a normal battle I can get 10 rage on turn 1 (phoenix, inquisitors + a few ranged units).
Has anyone upgraded the ball a few times, does it become an essential killing machine, or just a too expensive gimmic than you never use?
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