diff --git a/packages/web/src/App.svelte b/packages/web/src/App.svelte
index 975798f..3dbb377 100644
--- a/packages/web/src/App.svelte
+++ b/packages/web/src/App.svelte
@@ -1,5 +1,5 @@
 <script lang="ts">
-  import { attentionLabel, net } from "./net.svelte";
+  import { attentionLabel, net, spellName } from "./net.svelte";
   import Board from "./Board.svelte";
   import { PLAYER_COLORS, wizardColor } from "./colors";
   import Card from "./Card.svelte";
@@ -432,6 +432,11 @@
     tacks: "handful-of-tacks", pit: "create-pit", safe: "safe",
   };
 
+  /** Sustained ids include engine constructs the card library cannot show. */
+  function realCard(cardId: string): boolean {
+    try { cardDef(cardId); return true; } catch { return false; }
+  }
+
   function creatureStats(c: NonNullable<GameView["creatures"]>[number]): string {
     const hp = Number.isFinite(c.maxDamage)
       ? `${c.maxDamage - c.damage} of ${c.maxDamage} hits left`
@@ -1073,10 +1078,11 @@
                 {/each}
                 {#each spellsOn as e (e.id)}
                   <button class="table-card spell-chip" onclick={() => {
+                    if (!realCard(e.cardId)) return;
                     peekCard = { instanceId: `peek-${e.id}`, cardId: e.cardId };
                     peekCreatureId = null;
                   }}>
-                    ✦ {cardDef(e.cardId).name} · {e.remainingTurns}
+                    ✦ {spellName(e.cardId)} · {e.remainingTurns}
                   </button>
                 {/each}
               </div>
diff --git a/packages/web/src/net.svelte.ts b/packages/web/src/net.svelte.ts
index f76ecd0..fb29c96 100644
--- a/packages/web/src/net.svelte.ts
+++ b/packages/web/src/net.svelte.ts
@@ -9,6 +9,20 @@ const SERVER_URL =
     ? "ws://localhost:8787"
     : `${location.protocol === "https:" ? "wss" : "ws"}://${location.host}/ws`);
 
+/** Sustained-effect ids that are engine constructs, not printed cards. */
+const SYNTHETIC_SPELL_NAMES: Record<string, string> = { "sticky-web": "Sticky Wand webs" };
+
+/** Card name lookup that survives synthetic ids — render code must never throw. */
+export function spellName(cardId: string): string {
+  const synthetic = SYNTHETIC_SPELL_NAMES[cardId];
+  if (synthetic) return synthetic;
+  try {
+    return cardDef(cardId).name;
+  } catch {
+    return cardId;
+  }
+}
+
 export function humanize(e: GameEvent): string | null {
   switch (e.type) {
     case "gameStarted": return `Game started — ${e.players.join(", ")}. ${e.firstPlayer} goes first.`;
@@ -43,8 +57,8 @@ export function humanize(e: GameEvent): string | null {
       : `${e.defender} is too small to hit — the attack misses!`;
     case "damageImmune": return `${e.player} is stone — the damage has no effect.`;
     case "lifeGained": return `${e.player} gains ${e.amount} life (${e.source}) — now ${e.lifeAfter}.`;
-    case "spellSustained": return `${cardDef(e.cardId).name} settles over ${e.target} (${e.turns} turn${e.turns === 1 ? "" : "s"}).`;
-    case "spellExpired": return `${cardDef(e.cardId).name} wears off ${e.target}.`;
+    case "spellSustained": return `${spellName(e.cardId)} settles over ${e.target} (${e.turns} turn${e.turns === 1 ? "" : "s"}).`;
+    case "spellExpired": return `${spellName(e.cardId)} wears off ${e.target}.`;
     case "teleported": return e.by === e.player
       ? `${e.player} teleports across the maze!`
       : `${e.player} is teleported away by ${e.by}!`;