I have a number of suggestions for you -

Winding Constrictor - Has a nice synergy effect with Meren of Clan Nel Toth, as it will double the number of experience counters she earns per creature death.

Walking Ballista - Synergizes with Meren of Clan Nel Toth as it can continually be played for 0, it dies (as it has 0 toughness) and can be brought back to the battlefield for 0. Every time Ballista dies Meren gets 1 experience counter. To make things better, it also synergizes with Winding Constrictor.

Treasure Keeper - As this creature dies you can replace it with another permanent that costs or less. Seems useful.

Shriekmaw - Play this creature for it's evoke cost for some targeted removal. As you get more experience counters you can just keep returning it for more and more removal.

That's it for now, when I find more ideas i'll post em' here.