The game is getting interesting. The recent modification of rule 3b might come into play here. As of the recent strip #1302, Calder has appeared in 9 strips (since he telepathic thought bubbles in #1294). He isn't dead yet but Roy wants to wrap up the encounter soon and it doesn't look like the encounter can end peacefully. If Calder is confirmed dead in the next strip then he wasn't a significant death. If Calder survives next strip then he becomes a significant character who may die soon and you can bet on him. Everyone else around probably counts as a significant character already, and some of them could get killed here. In particular, Mimi appeared in more than enough strips: #1237, #1238, #1241, #1243 1st, #1281, #1283, likely #1284 (#1283 4th shows a mimic transforming to a pillow and it seems like that's Mimi), #1288, #1290 1st (transformed to a box), #1292, #1293, #1294, #1295, #1296, #1297.