Kolaghan's change is also great, though I feel I must justify the inclusion of deathtouch: since Kolaghan is somewhat smaller than the other dragons in this set, I wanted him to be able to take those guys out
Lightning, Army of One stacks up beautifully, and if followed up with additional combats or direct damage after that which will be multiplied by 4
Mikaeus can kill the table with Walking Ballista if he's got a sacrifice outlet on the field, but I'm not aware of any replacements for Dina's favorite enchantment, Exquisite Blood
If you don't want to smash something, you can always use the second mode to steal the card that an opponent searched for with Vampiric Tutor before they draw it
These include mana generators such as Skirge Familiar or Bog Witch
(If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.) If Maester Seymour is no longer on the battlefield when its first ability resolves, use its power as it last existed on the battlefield to determine how many +1/+1 counters to put on the target creature